http://git-wip-us.apache.org/repos/asf/tajo/blob/aa699c70/tajo-core/src/main/java/org/apache/tajo/ws/rs/resources/TablesResource.java
----------------------------------------------------------------------
diff --git 
a/tajo-core/src/main/java/org/apache/tajo/ws/rs/resources/TablesResource.java 
b/tajo-core/src/main/java/org/apache/tajo/ws/rs/resources/TablesResource.java
index 3dba02f..3afe7c8 100644
--- 
a/tajo-core/src/main/java/org/apache/tajo/ws/rs/resources/TablesResource.java
+++ 
b/tajo-core/src/main/java/org/apache/tajo/ws/rs/resources/TablesResource.java
@@ -121,7 +121,7 @@ public class TablesResource {
       }
 
       Collection<String> tableNames = 
catalogService.getAllTableNames(databaseName);
-      Map<String, Collection<String>> tableNamesMap = new HashMap<String, 
Collection<String>>();
+      Map<String, Collection<String>> tableNamesMap = new HashMap<>();
       tableNamesMap.put(tablesKeyName, tableNames);
       return Response.ok(tableNamesMap).build();
     }

http://git-wip-us.apache.org/repos/asf/tajo/blob/aa699c70/tajo-core/src/main/resources/webapps/admin/cluster.jsp
----------------------------------------------------------------------
diff --git a/tajo-core/src/main/resources/webapps/admin/cluster.jsp 
b/tajo-core/src/main/resources/webapps/admin/cluster.jsp
index 7aad8d4..fd942bd 100644
--- a/tajo-core/src/main/resources/webapps/admin/cluster.jsp
+++ b/tajo-core/src/main/resources/webapps/admin/cluster.jsp
@@ -39,17 +39,17 @@
   String masterLabel = socketAddress.getAddress().getHostName()+ ":" + 
socketAddress.getPort();
 
   Map<Integer, NodeStatus> nodes = 
master.getContext().getResourceManager().getNodes();
-  List<Integer> wokerKeys = new ArrayList<Integer>(nodes.keySet());
+  List<Integer> wokerKeys = new ArrayList<>(nodes.keySet());
   Collections.sort(wokerKeys);
 
   int runningQueryMasterTasks = 0;
 
-  Set<NodeStatus> liveNodes = new TreeSet<NodeStatus>();
-  Set<NodeStatus> deadNodes = new TreeSet<NodeStatus>();
-  Set<NodeStatus> decommissionNodes = new TreeSet<NodeStatus>();
+  Set<NodeStatus> liveNodes = new TreeSet<>();
+  Set<NodeStatus> deadNodes = new TreeSet<>();
+  Set<NodeStatus> decommissionNodes = new TreeSet<>();
 
-  Set<NodeStatus> liveQueryMasters = new TreeSet<NodeStatus>();
-  Set<NodeStatus> deadQueryMasters = new TreeSet<NodeStatus>();
+  Set<NodeStatus> liveQueryMasters = new TreeSet<>();
+  Set<NodeStatus> deadQueryMasters = new TreeSet<>();
 
   for(NodeStatus eachNode: nodes.values()) {
     liveQueryMasters.add(eachNode);

http://git-wip-us.apache.org/repos/asf/tajo/blob/aa699c70/tajo-core/src/main/resources/webapps/admin/functions.jsp
----------------------------------------------------------------------
diff --git a/tajo-core/src/main/resources/webapps/admin/functions.jsp 
b/tajo-core/src/main/resources/webapps/admin/functions.jsp
index cf3ddc5..2006ef5 100644
--- a/tajo-core/src/main/resources/webapps/admin/functions.jsp
+++ b/tajo-core/src/main/resources/webapps/admin/functions.jsp
@@ -28,7 +28,7 @@
     TajoMaster master = (TajoMaster) 
StaticHttpServer.getInstance().getAttribute("tajo.info.server.object");
     CatalogService catalog = master.getCatalog();
 
-    List<FunctionDesc> functions = new 
ArrayList<FunctionDesc>(catalog.getFunctions());
+    List<FunctionDesc> functions = new ArrayList<>(catalog.getFunctions());
     Collections.sort(functions);
 %>
 

http://git-wip-us.apache.org/repos/asf/tajo/blob/aa699c70/tajo-core/src/main/resources/webapps/admin/query.jsp
----------------------------------------------------------------------
diff --git a/tajo-core/src/main/resources/webapps/admin/query.jsp 
b/tajo-core/src/main/resources/webapps/admin/query.jsp
index bcf7766..e44ac8c 100644
--- a/tajo-core/src/main/resources/webapps/admin/query.jsp
+++ b/tajo-core/src/main/resources/webapps/admin/query.jsp
@@ -39,11 +39,11 @@
   String masterLabel = socketAddress.getAddress().getHostName()+ ":" + 
socketAddress.getPort();
 
   List<QueryInProgress> submittedQueries =
-          new 
ArrayList<QueryInProgress>(master.getContext().getQueryJobManager().getSubmittedQueries());
+          new 
ArrayList<>(master.getContext().getQueryJobManager().getSubmittedQueries());
   JSPUtil.sortQueryInProgress(submittedQueries, true);
 
   List<QueryInProgress> runningQueries =
-          new 
ArrayList<QueryInProgress>(master.getContext().getQueryJobManager().getRunningQueries());
+          new 
ArrayList<>(master.getContext().getQueryJobManager().getRunningQueries());
   JSPUtil.sortQueryInProgress(runningQueries, true);
 
   int currentPage = 1;
@@ -64,7 +64,7 @@
   SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
 
   Map<Integer, NodeStatus> workers = 
master.getContext().getResourceManager().getNodes();
-  Map<String, Integer> portMap = new HashMap<String, Integer>();
+  Map<String, Integer> portMap = new HashMap<>();
 
   Collection<Integer> queryMasters = 
master.getContext().getResourceManager().getQueryMasters();
   if (queryMasters == null || queryMasters.isEmpty()) {

http://git-wip-us.apache.org/repos/asf/tajo/blob/aa699c70/tajo-core/src/main/resources/webapps/admin/querytasks.jsp
----------------------------------------------------------------------
diff --git a/tajo-core/src/main/resources/webapps/admin/querytasks.jsp 
b/tajo-core/src/main/resources/webapps/admin/querytasks.jsp
index a7b26ae..f2dc68b 100644
--- a/tajo-core/src/main/resources/webapps/admin/querytasks.jsp
+++ b/tajo-core/src/main/resources/webapps/admin/querytasks.jsp
@@ -76,7 +76,7 @@
 
   Collection<NodeStatus> allWorkers = 
master.getContext().getResourceManager().getNodes().values();
 
-  Map<String, NodeStatus> nodeMap = new HashMap<String, NodeStatus>();
+  Map<String, NodeStatus> nodeMap = new HashMap<>();
   if(allWorkers != null) {
     for(NodeStatus eachWorker: allWorkers) {
       nodeMap.put(eachWorker.getConnectionInfo().getHostAndPeerRpcPort(), 
eachWorker);
@@ -189,7 +189,7 @@
     <input type="hidden" name="startTime" value="<%=startTime%>"/>
   </form>
 <%
-  List<TaskHistory> filteredTasks = new ArrayList<TaskHistory>();
+  List<TaskHistory> filteredTasks = new ArrayList<>();
   for(TaskHistory eachTask: allTasks) {
     if (!"ALL".equals(status)) {
       if (!status.equals(eachTask.getState().toString())) {

http://git-wip-us.apache.org/repos/asf/tajo/blob/aa699c70/tajo-core/src/main/resources/webapps/worker/queryplan.jsp
----------------------------------------------------------------------
diff --git a/tajo-core/src/main/resources/webapps/worker/queryplan.jsp 
b/tajo-core/src/main/resources/webapps/worker/queryplan.jsp
index 422edfc..8918224 100644
--- a/tajo-core/src/main/resources/webapps/worker/queryplan.jsp
+++ b/tajo-core/src/main/resources/webapps/worker/queryplan.jsp
@@ -46,7 +46,7 @@
 
   Query query = queryMasterTask.getQuery();
 
-  Map<ExecutionBlockId, Stage> stageMap = new HashMap<ExecutionBlockId, 
Stage>();
+  Map<ExecutionBlockId, Stage> stageMap = new HashMap<>();
 
   for(Stage eachStage : query.getStages()) {
     stageMap.put(eachStage.getId(), eachStage);
@@ -102,7 +102,7 @@
   String curIdStr = null;
   int x=35, y=1;
   int pos;
-  List<StageInfo> stageInfos = new ArrayList<StageInfo>();
+  List<StageInfo> stageInfos = new ArrayList<>();
 
   stageInfos.add(new StageInfo(masterPlan.getRoot(), null, null, x, y, 0));
 

http://git-wip-us.apache.org/repos/asf/tajo/blob/aa699c70/tajo-core/src/main/resources/webapps/worker/querytasks.jsp
----------------------------------------------------------------------
diff --git a/tajo-core/src/main/resources/webapps/worker/querytasks.jsp 
b/tajo-core/src/main/resources/webapps/worker/querytasks.jsp
index caaec35..d5e9a9f 100644
--- a/tajo-core/src/main/resources/webapps/worker/querytasks.jsp
+++ b/tajo-core/src/main/resources/webapps/worker/querytasks.jsp
@@ -64,7 +64,7 @@
   List<TajoProtos.WorkerConnectionInfoProto> allWorkers = 
tajoWorker.getWorkerContext()
             .getQueryMasterManagerService().getQueryMaster().getAllWorker();
 
-  Map<Integer, TajoProtos.WorkerConnectionInfoProto> workerMap = new 
HashMap<Integer, TajoProtos.WorkerConnectionInfoProto>();
+  Map<Integer, TajoProtos.WorkerConnectionInfoProto> workerMap = new 
HashMap<>();
   if(allWorkers != null) {
     for(TajoProtos.WorkerConnectionInfoProto eachWorker: allWorkers) {
       workerMap.put(eachWorker.getId(), eachWorker);
@@ -204,7 +204,7 @@
     <input type="hidden" name="sortOrder" value="<%=sortOrder%>"/>
   </form>
 <%
-  List<Task> filteredTask = new ArrayList<Task>();
+  List<Task> filteredTask = new ArrayList<>();
   for(Task eachTask : allTasks) {
     if (!"ALL".equals(status)) {
       if (!status.equals(eachTask.getLastAttemptStatus().toString())) {

http://git-wip-us.apache.org/repos/asf/tajo/blob/aa699c70/tajo-jdbc/src/main/java/org/apache/tajo/jdbc/TajoDatabaseMetaData.java
----------------------------------------------------------------------
diff --git 
a/tajo-jdbc/src/main/java/org/apache/tajo/jdbc/TajoDatabaseMetaData.java 
b/tajo-jdbc/src/main/java/org/apache/tajo/jdbc/TajoDatabaseMetaData.java
index f22bafe..ad0fd3c 100644
--- a/tajo-jdbc/src/main/java/org/apache/tajo/jdbc/TajoDatabaseMetaData.java
+++ b/tajo-jdbc/src/main/java/org/apache/tajo/jdbc/TajoDatabaseMetaData.java
@@ -364,7 +364,7 @@ public class TajoDatabaseMetaData implements 
DatabaseMetaData {
   @Override
   public ResultSet getTables(@Nullable String catalog, @Nullable String 
schemaPattern,
                              @Nullable String tableNamePattern, @Nullable 
String [] types) throws SQLException {
-    final List<MetaDataTuple> resultTables = new ArrayList<MetaDataTuple>();
+    final List<MetaDataTuple> resultTables = new ArrayList<>();
     String regtableNamePattern = convertPattern(tableNamePattern == null ? 
null : tableNamePattern);
 
     List<String> targetCatalogs = Lists.newArrayList();
@@ -440,7 +440,7 @@ public class TajoDatabaseMetaData implements 
DatabaseMetaData {
 
     databaseNames = conn.getCatalogAdminClient().getAllDatabaseNames();
 
-    List<MetaDataTuple> tuples = new ArrayList<MetaDataTuple>();
+    List<MetaDataTuple> tuples = new ArrayList<>();
     for (String databaseName : databaseNames) {
       MetaDataTuple tuple = new MetaDataTuple(1);
       tuple.put(0, new TextDatum(databaseName));
@@ -455,7 +455,7 @@ public class TajoDatabaseMetaData implements 
DatabaseMetaData {
 
   @Override
   public ResultSet getTableTypes() throws SQLException {
-    List<MetaDataTuple> columns = new ArrayList<MetaDataTuple>();
+    List<MetaDataTuple> columns = new ArrayList<>();
     MetaDataTuple tuple = new MetaDataTuple(2);
     tuple.put(0, new TextDatum("TABLE"));
     columns.add(tuple);
@@ -471,7 +471,7 @@ public class TajoDatabaseMetaData implements 
DatabaseMetaData {
   @Override
   public ResultSet getUDTs(String catalog, String schemaPattern, String 
typeNamePattern, int[] types)
       throws SQLException {
-    List<MetaDataTuple> columns = new ArrayList<MetaDataTuple>();
+    List<MetaDataTuple> columns = new ArrayList<>();
 
     return new TajoMetaDataResultSet(
         Arrays.asList("TYPE_CAT", "TYPE_SCHEM", "TYPE_NAME", "CLASS_NAME", 
"DATA_TYPE"
@@ -490,7 +490,7 @@ public class TajoDatabaseMetaData implements 
DatabaseMetaData {
       targetCatalogs.add(catalog);
     }
 
-    List<MetaDataTuple> columns = new ArrayList<MetaDataTuple>();
+    List<MetaDataTuple> columns = new ArrayList<>();
     try {
       if (targetCatalogs.isEmpty()) {
         
targetCatalogs.addAll(conn.getCatalogAdminClient().getAllDatabaseNames());
@@ -641,7 +641,7 @@ public class TajoDatabaseMetaData implements 
DatabaseMetaData {
 
   @Override
   public ResultSet getTypeInfo() throws SQLException {
-    List<MetaDataTuple> tuples = new ArrayList<MetaDataTuple>();
+    List<MetaDataTuple> tuples = new ArrayList<>();
     for (Datum[] eachDatums: TajoTypeUtil.getTypeInfos()) {
       MetaDataTuple tuple = new MetaDataTuple(eachDatums.length);
       for (int i = 0; i < eachDatums.length; i++) {

http://git-wip-us.apache.org/repos/asf/tajo/blob/aa699c70/tajo-jdbc/src/main/java/org/apache/tajo/jdbc/TajoPreparedStatement.java
----------------------------------------------------------------------
diff --git 
a/tajo-jdbc/src/main/java/org/apache/tajo/jdbc/TajoPreparedStatement.java 
b/tajo-jdbc/src/main/java/org/apache/tajo/jdbc/TajoPreparedStatement.java
index 6b47f97..3793bb0 100644
--- a/tajo-jdbc/src/main/java/org/apache/tajo/jdbc/TajoPreparedStatement.java
+++ b/tajo-jdbc/src/main/java/org/apache/tajo/jdbc/TajoPreparedStatement.java
@@ -37,7 +37,7 @@ public class TajoPreparedStatement extends TajoStatement 
implements PreparedStat
   /**
    * save the SQL parameters {paramLoc:paramValue}
    */
-  private final HashMap<Integer, String> parameters=new HashMap<Integer, 
String>();
+  private final HashMap<Integer, String> parameters= new HashMap<>();
 
   /**
    * keep the current ResultRet update count

http://git-wip-us.apache.org/repos/asf/tajo/blob/aa699c70/tajo-jdbc/src/main/java/org/apache/tajo/jdbc/util/QueryStringDecoder.java
----------------------------------------------------------------------
diff --git 
a/tajo-jdbc/src/main/java/org/apache/tajo/jdbc/util/QueryStringDecoder.java 
b/tajo-jdbc/src/main/java/org/apache/tajo/jdbc/util/QueryStringDecoder.java
index 9ec9340..86d1b1a 100644
--- a/tajo-jdbc/src/main/java/org/apache/tajo/jdbc/util/QueryStringDecoder.java
+++ b/tajo-jdbc/src/main/java/org/apache/tajo/jdbc/util/QueryStringDecoder.java
@@ -59,7 +59,7 @@ public class QueryStringDecoder {
   }
   
   protected void decodeParams() throws MalformedURLException, 
UnsupportedEncodingException {
-    params = new HashMap<String, List<String>>();
+    params = new HashMap<>();
     String queries = getQueries();
     
     if (queries != null && !queries.isEmpty()) {
@@ -112,7 +112,7 @@ public class QueryStringDecoder {
     List<String> valueList = params.get(name);
     
     if (valueList == null) {
-      valueList = new ArrayList<String>();
+      valueList = new ArrayList<>();
       params.put(name, valueList);
     }
     

http://git-wip-us.apache.org/repos/asf/tajo/blob/aa699c70/tajo-jdbc/src/test/java/org/apache/tajo/jdbc/TestTajoDatabaseMetaData.java
----------------------------------------------------------------------
diff --git 
a/tajo-jdbc/src/test/java/org/apache/tajo/jdbc/TestTajoDatabaseMetaData.java 
b/tajo-jdbc/src/test/java/org/apache/tajo/jdbc/TestTajoDatabaseMetaData.java
index 8ee6755..3107af9 100644
--- a/tajo-jdbc/src/test/java/org/apache/tajo/jdbc/TestTajoDatabaseMetaData.java
+++ b/tajo-jdbc/src/test/java/org/apache/tajo/jdbc/TestTajoDatabaseMetaData.java
@@ -43,7 +43,7 @@ public class TestTajoDatabaseMetaData extends 
QueryTestCaseBase {
   }
 
   public static List<String> getListFromResultSet(ResultSet resultSet, String 
columnName) throws SQLException {
-    List<String> list = new ArrayList<String>();
+    List<String> list = new ArrayList<>();
     while(resultSet.next()) {
       list.add(resultSet.getString(columnName));
     }
@@ -202,7 +202,7 @@ public class TestTajoDatabaseMetaData extends 
QueryTestCaseBase {
         TajoConstants.DEFAULT_DATABASE_NAME);
     Connection conn = DriverManager.getConnection(connUri);
 
-    Map<String,List<String>> tables = new HashMap<String,List<String>>();
+    Map<String,List<String>> tables = new HashMap<>();
     assertDatabaseNotExists("db_1");
     executeString("CREATE DATABASE db_1");
     assertDatabaseExists("db_1");
@@ -277,7 +277,7 @@ public class TestTajoDatabaseMetaData extends 
QueryTestCaseBase {
       // db<i>.tb<j>, i = {1,2}, 0 <= j < 2
       // db<i>.table_<j>, i = {1,2}, 0 <= j < 2
 
-      Map<String,List<String>> tables = new HashMap<String,List<String>>();
+      Map<String,List<String>> tables = new HashMap<>();
       for (int j = 1; j <= 2; j++) {
         String dbName = "db" + j;
         assertDatabaseNotExists(dbName);

http://git-wip-us.apache.org/repos/asf/tajo/blob/aa699c70/tajo-jdbc/src/test/java/org/apache/tajo/jdbc/TestTajoJdbc.java
----------------------------------------------------------------------
diff --git a/tajo-jdbc/src/test/java/org/apache/tajo/jdbc/TestTajoJdbc.java 
b/tajo-jdbc/src/test/java/org/apache/tajo/jdbc/TestTajoJdbc.java
index f8d5c45..d29291e 100644
--- a/tajo-jdbc/src/test/java/org/apache/tajo/jdbc/TestTajoJdbc.java
+++ b/tajo-jdbc/src/test/java/org/apache/tajo/jdbc/TestTajoJdbc.java
@@ -307,9 +307,9 @@ public class TestTajoJdbc extends QueryTestCaseBase {
       int numCols = rsmd.getColumnCount();
       assertEquals(5, numCols);
 
-      Set<String> retrivedViaJavaAPI = new 
HashSet<String>(client.getTableList("default"));
+      Set<String> retrivedViaJavaAPI = new 
HashSet<>(client.getTableList("default"));
 
-      Set<String> retrievedViaJDBC = new HashSet<String>();
+      Set<String> retrievedViaJDBC = new HashSet<>();
       while (rs.next()) {
         retrievedViaJDBC.add(rs.getString("TABLE_NAME"));
       }

http://git-wip-us.apache.org/repos/asf/tajo/blob/aa699c70/tajo-maven-plugins/src/main/java/org/apache/tajo/maven/plugin/protoc/ProtocMojo.java
----------------------------------------------------------------------
diff --git 
a/tajo-maven-plugins/src/main/java/org/apache/tajo/maven/plugin/protoc/ProtocMojo.java
 
b/tajo-maven-plugins/src/main/java/org/apache/tajo/maven/plugin/protoc/ProtocMojo.java
index 498f85d..e42ac6b 100644
--- 
a/tajo-maven-plugins/src/main/java/org/apache/tajo/maven/plugin/protoc/ProtocMojo.java
+++ 
b/tajo-maven-plugins/src/main/java/org/apache/tajo/maven/plugin/protoc/ProtocMojo.java
@@ -58,11 +58,11 @@ public class ProtocMojo extends AbstractMojo {
       if (protocCommand == null || protocCommand.trim().isEmpty()) {
         protocCommand = "protoc";
       }
-      List<String> command = new ArrayList<String>();
+      List<String> command = new ArrayList<>();
       command.add(protocCommand);
       command.add("--version");
       Exec exec = new Exec(this);
-      List<String> out = new ArrayList<String>();
+      List<String> out = new ArrayList<>();
       if (exec.run(command, out) == 127) {
         getLog().error("protoc, not found at: " + protocCommand);
         throw new MojoExecutionException("protoc failure");        
@@ -85,7 +85,7 @@ public class ProtocMojo extends AbstractMojo {
             output);
         }
       }
-      command = new ArrayList<String>();
+      command = new ArrayList<>();
       command.add(protocCommand);
       command.add("--java_out=" + output.getCanonicalPath());
       if (imports != null) {
@@ -97,7 +97,7 @@ public class ProtocMojo extends AbstractMojo {
         command.add(f.getCanonicalPath());
       }
       exec = new Exec(this);
-      out = new ArrayList<String>();
+      out = new ArrayList<>();
       if (exec.run(command, out) != 0) {
         getLog().error("protoc compiler error");
         for (String s : out) {

http://git-wip-us.apache.org/repos/asf/tajo/blob/aa699c70/tajo-maven-plugins/src/main/java/org/apache/tajo/maven/plugin/util/Exec.java
----------------------------------------------------------------------
diff --git 
a/tajo-maven-plugins/src/main/java/org/apache/tajo/maven/plugin/util/Exec.java 
b/tajo-maven-plugins/src/main/java/org/apache/tajo/maven/plugin/util/Exec.java
index 89ba6fb..c657cbf 100644
--- 
a/tajo-maven-plugins/src/main/java/org/apache/tajo/maven/plugin/util/Exec.java
+++ 
b/tajo-maven-plugins/src/main/java/org/apache/tajo/maven/plugin/util/Exec.java
@@ -88,7 +88,7 @@ public class Exec {
      */
     public OutputBufferThread(InputStream is) {
       this.setDaemon(true);
-      output = new ArrayList<String>();
+      output = new ArrayList<>();
       reader = new BufferedReader(new InputStreamReader(is));
     }
 

http://git-wip-us.apache.org/repos/asf/tajo/blob/aa699c70/tajo-maven-plugins/src/main/java/org/apache/tajo/maven/plugin/versioninfo/VersionInfoMojo.java
----------------------------------------------------------------------
diff --git 
a/tajo-maven-plugins/src/main/java/org/apache/tajo/maven/plugin/versioninfo/VersionInfoMojo.java
 
b/tajo-maven-plugins/src/main/java/org/apache/tajo/maven/plugin/versioninfo/VersionInfoMojo.java
index 5347f40..44db8ee 100644
--- 
a/tajo-maven-plugins/src/main/java/org/apache/tajo/maven/plugin/versioninfo/VersionInfoMojo.java
+++ 
b/tajo-maven-plugins/src/main/java/org/apache/tajo/maven/plugin/versioninfo/VersionInfoMojo.java
@@ -115,7 +115,7 @@ public class VersionInfoMojo extends AbstractMojo {
   private SCM determineSCM() throws Exception {
     Exec exec = new Exec(this);
     SCM scm = SCM.NONE;
-    scmOut = new ArrayList<String>();
+    scmOut = new ArrayList<>();
     int ret = exec.run(Arrays.asList(svnCommand, "info"), scmOut);
     if (ret == 0) {
       scm = SCM.SVN;

http://git-wip-us.apache.org/repos/asf/tajo/blob/aa699c70/tajo-plan/src/main/java/org/apache/tajo/plan/ExprAnnotator.java
----------------------------------------------------------------------
diff --git a/tajo-plan/src/main/java/org/apache/tajo/plan/ExprAnnotator.java 
b/tajo-plan/src/main/java/org/apache/tajo/plan/ExprAnnotator.java
index 89089e0..f4c11cd 100644
--- a/tajo-plan/src/main/java/org/apache/tajo/plan/ExprAnnotator.java
+++ b/tajo-plan/src/main/java/org/apache/tajo/plan/ExprAnnotator.java
@@ -119,7 +119,7 @@ public class ExprAnnotator extends 
BaseAlgebraVisitor<ExprAnnotator.Context, Eva
 
     // If one of both is NULL, it just returns the original types without 
casting.
     if (lhsType == Type.NULL_TYPE || rhsType == Type.NULL_TYPE) {
-      return new Pair<EvalNode, EvalNode>(lhs, rhs);
+      return new Pair<>(lhs, rhs);
     }
 
     Type toBeCasted = 
TUtil.getFromNestedMap(CatalogUtil.OPERATION_CASTING_MAP, lhsType, rhsType);
@@ -133,7 +133,7 @@ public class ExprAnnotator extends 
BaseAlgebraVisitor<ExprAnnotator.Context, Eva
       }
     }
 
-    return new Pair<EvalNode, EvalNode>(lhs, rhs);
+    return new Pair<>(lhs, rhs);
   }
 
   /**

http://git-wip-us.apache.org/repos/asf/tajo/blob/aa699c70/tajo-plan/src/main/java/org/apache/tajo/plan/ExprNormalizer.java
----------------------------------------------------------------------
diff --git a/tajo-plan/src/main/java/org/apache/tajo/plan/ExprNormalizer.java 
b/tajo-plan/src/main/java/org/apache/tajo/plan/ExprNormalizer.java
index ff7eabd..ab1914b 100644
--- a/tajo-plan/src/main/java/org/apache/tajo/plan/ExprNormalizer.java
+++ b/tajo-plan/src/main/java/org/apache/tajo/plan/ExprNormalizer.java
@@ -91,9 +91,9 @@ class ExprNormalizer extends 
SimpleAlgebraVisitor<ExprNormalizer.ExprNormalizedR
 
     Expr baseExpr; // outmost expressions, which can includes one or more 
references of the results of aggregation
                    // function.
-    List<NamedExpr> aggExprs = new ArrayList<NamedExpr>(); // aggregation 
functions
-    List<NamedExpr> scalarExprs = new ArrayList<NamedExpr>(); // scalar 
expressions which can be referred
-    List<NamedExpr> windowAggExprs = new ArrayList<NamedExpr>(); // window 
expressions which can be referred
+    List<NamedExpr> aggExprs = new ArrayList<>(); // aggregation functions
+    List<NamedExpr> scalarExprs = new ArrayList<>(); // scalar expressions 
which can be referred
+    List<NamedExpr> windowAggExprs = new ArrayList<>(); // window expressions 
which can be referred
     Set<WindowSpecReferences> windowSpecs = Sets.newLinkedHashSet();
 
     public ExprNormalizedResult(LogicalPlanner.PlanContext context, boolean 
tryBinaryCommonTermsElimination) {
@@ -118,7 +118,7 @@ class ExprNormalizer extends 
SimpleAlgebraVisitor<ExprNormalizer.ExprNormalizedR
   public ExprNormalizedResult normalize(LogicalPlanner.PlanContext context, 
Expr expr, boolean subexprElimination)
       throws TajoException {
     ExprNormalizedResult exprNormalizedResult = new 
ExprNormalizedResult(context, subexprElimination);
-    Stack<Expr> stack = new Stack<Expr>();
+    Stack<Expr> stack = new Stack<>();
     stack.push(expr);
     visit(exprNormalizedResult, new Stack<Expr>(), expr);
     exprNormalizedResult.baseExpr = stack.pop();

http://git-wip-us.apache.org/repos/asf/tajo/blob/aa699c70/tajo-plan/src/main/java/org/apache/tajo/plan/LogicalOptimizer.java
----------------------------------------------------------------------
diff --git a/tajo-plan/src/main/java/org/apache/tajo/plan/LogicalOptimizer.java 
b/tajo-plan/src/main/java/org/apache/tajo/plan/LogicalOptimizer.java
index 96617d1..ecb478c 100644
--- a/tajo-plan/src/main/java/org/apache/tajo/plan/LogicalOptimizer.java
+++ b/tajo-plan/src/main/java/org/apache/tajo/plan/LogicalOptimizer.java
@@ -87,7 +87,7 @@ public class LogicalOptimizer {
     rulesBeforeJoinOpt.rewrite(new LogicalPlanRewriteRuleContext(context, 
plan, catalog));
 
     DirectedGraphCursor<String, BlockEdge> blockCursor =
-        new DirectedGraphCursor<String, BlockEdge>(plan.getQueryBlockGraph(), 
plan.getRootBlock().getName());
+            new DirectedGraphCursor<>(plan.getQueryBlockGraph(), 
plan.getRootBlock().getName());
 
     if (context == null || context.getBool(SessionVars.TEST_JOIN_OPT_ENABLED)) 
{
       // default is true
@@ -121,7 +121,7 @@ public class LogicalOptimizer {
       JoinNode old = PlannerUtil.findTopNode(block.getRoot(), NodeType.JOIN);
 
       JoinTargetCollector collector = new JoinTargetCollector();
-      Set<Target> targets = new LinkedHashSet<Target>();
+      Set<Target> targets = new LinkedHashSet<>();
       collector.visitJoin(targets, plan, block, old, new Stack<LogicalNode>());
 
       if (targets.size() == 0) {
@@ -158,9 +158,9 @@ public class LogicalOptimizer {
                                                                JoinNode 
newJoinNode) {
     // Gather filters from remaining join edges
     Collection<JoinEdge> joinEdges = 
joinGraphContext.getJoinGraph().getEdgesAll();
-    Collection<EvalNode> markAsEvaluated = new 
HashSet<EvalNode>(joinGraphContext.getEvaluatedJoinConditions());
+    Collection<EvalNode> markAsEvaluated = new 
HashSet<>(joinGraphContext.getEvaluatedJoinConditions());
     markAsEvaluated.addAll(joinGraphContext.getEvaluatedJoinFilters());
-    Set<EvalNode> remainingQuals = new 
HashSet<EvalNode>(joinGraphContext.getCandidateJoinFilters());
+    Set<EvalNode> remainingQuals = new 
HashSet<>(joinGraphContext.getCandidateJoinFilters());
     for (JoinEdge eachEdge : joinEdges) {
       for (EvalNode eachQual : eachEdge.getJoinQual()) {
         if (!markAsEvaluated.contains(eachQual)) {

http://git-wip-us.apache.org/repos/asf/tajo/blob/aa699c70/tajo-plan/src/main/java/org/apache/tajo/plan/LogicalPlan.java
----------------------------------------------------------------------
diff --git a/tajo-plan/src/main/java/org/apache/tajo/plan/LogicalPlan.java 
b/tajo-plan/src/main/java/org/apache/tajo/plan/LogicalPlan.java
index b7df810..457cb2c 100644
--- a/tajo-plan/src/main/java/org/apache/tajo/plan/LogicalPlan.java
+++ b/tajo-plan/src/main/java/org/apache/tajo/plan/LogicalPlan.java
@@ -64,11 +64,11 @@ public class LogicalPlan {
   private Integer noNameColumnId = 0;
 
   /** a map from between a block name to a block plan */
-  private Map<String, QueryBlock> queryBlocks = new LinkedHashMap<String, 
QueryBlock>();
-  private Map<Integer, LogicalNode> nodeMap = new HashMap<Integer, 
LogicalNode>();
-  private Map<Integer, QueryBlock> queryBlockByPID = new HashMap<Integer, 
QueryBlock>();
+  private Map<String, QueryBlock> queryBlocks = new LinkedHashMap<>();
+  private Map<Integer, LogicalNode> nodeMap = new HashMap<>();
+  private Map<Integer, QueryBlock> queryBlockByPID = new HashMap<>();
   private Map<String, String> exprToBlockNameMap = TUtil.newHashMap();
-  private SimpleDirectedGraph<String, BlockEdge> queryBlockGraph = new 
SimpleDirectedGraph<String, BlockEdge>();
+  private SimpleDirectedGraph<String, BlockEdge> queryBlockGraph = new 
SimpleDirectedGraph<>();
 
   /** planning and optimization log */
   private List<String> planingHistory = Lists.newArrayList();
@@ -266,7 +266,7 @@ public class LogicalPlan {
 
   public void removeBlock(QueryBlock block) {
     queryBlocks.remove(block.getName());
-    List<Integer> tobeRemoved = new ArrayList<Integer>();
+    List<Integer> tobeRemoved = new ArrayList<>();
     for (Map.Entry<Integer, QueryBlock> entry : queryBlockByPID.entrySet()) {
       tobeRemoved.add(entry.getKey());
     }
@@ -335,7 +335,7 @@ public class LogicalPlan {
       }
     }
     DirectedGraphCursor<String, BlockEdge> cursor =
-        new DirectedGraphCursor<String, BlockEdge>(queryBlockGraph, 
getRootBlock().getName());
+            new DirectedGraphCursor<>(queryBlockGraph, 
getRootBlock().getName());
     while(cursor.hasNext()) {
       QueryBlock block = getBlock(cursor.nextBlock());
       if (block.getPlanHistory().size() > 0) {

http://git-wip-us.apache.org/repos/asf/tajo/blob/aa699c70/tajo-plan/src/main/java/org/apache/tajo/plan/LogicalPlanner.java
----------------------------------------------------------------------
diff --git a/tajo-plan/src/main/java/org/apache/tajo/plan/LogicalPlanner.java 
b/tajo-plan/src/main/java/org/apache/tajo/plan/LogicalPlanner.java
index 3531ce7..7593a9b 100644
--- a/tajo-plan/src/main/java/org/apache/tajo/plan/LogicalPlanner.java
+++ b/tajo-plan/src/main/java/org/apache/tajo/plan/LogicalPlanner.java
@@ -397,8 +397,8 @@ public class LogicalPlanner extends 
BaseAlgebraVisitor<LogicalPlanner.PlanContex
     });
     addNamedExprs(block, referenceNames, normalizedExprList, 
windowSpecReferencesList, projection, targetsIds);
 
-    return new Pair<String[], ExprNormalizer.WindowSpecReferences 
[]>(referenceNames,
-        windowSpecReferencesList.toArray(new 
ExprNormalizer.WindowSpecReferences[windowSpecReferencesList.size()]));
+    return new Pair<>(referenceNames,
+            windowSpecReferencesList.toArray(new 
ExprNormalizer.WindowSpecReferences[windowSpecReferencesList.size()]));
   }
 
   private interface Matcher {
@@ -407,7 +407,7 @@ public class LogicalPlanner extends 
BaseAlgebraVisitor<LogicalPlanner.PlanContex
 
   public List<Integer> normalize(PlanContext context, Projection projection, 
ExprNormalizedResult [] normalizedExprList,
                                  Matcher matcher) throws TajoException {
-    List<Integer> targetIds = new ArrayList<Integer>();
+    List<Integer> targetIds = new ArrayList<>();
     for (int i = 0; i < projection.size(); i++) {
       NamedExpr namedExpr = projection.getNamedExprs()[i];
 
@@ -653,8 +653,8 @@ public class LogicalPlanner extends 
BaseAlgebraVisitor<LogicalPlanner.PlanContex
       windowAggNode.setInSchema(child.getOutSchema());
     }
 
-    List<String> winFuncRefs = new ArrayList<String>();
-    List<WindowFunctionEval> winFuncs = new ArrayList<WindowFunctionEval>();
+    List<String> winFuncRefs = new ArrayList<>();
+    List<WindowFunctionEval> winFuncs = new ArrayList<>();
     List<WindowSpec> rawWindowSpecs = Lists.newArrayList();
     for (Iterator<NamedExpr> it = 
block.namedExprsMgr.getIteratorForUnevaluatedExprs(); it.hasNext();) {
       NamedExpr rawTarget = it.next();
@@ -788,8 +788,8 @@ public class LogicalPlanner extends 
BaseAlgebraVisitor<LogicalPlanner.PlanContex
 
     groupbyNode.setGroupingColumns(new Column[] {});
 
-    Set<String> aggEvalNames = new LinkedHashSet<String>();
-    Set<AggregationFunctionCallEval> aggEvals = new 
LinkedHashSet<AggregationFunctionCallEval>();
+    Set<String> aggEvalNames = new LinkedHashSet<>();
+    Set<AggregationFunctionCallEval> aggEvals = new LinkedHashSet<>();
     boolean includeDistinctFunction = false;
     for (Iterator<NamedExpr> it = 
block.namedExprsMgr.getIteratorForUnevaluatedExprs(); it.hasNext();) {
       NamedExpr rawTarget = it.next();
@@ -1344,7 +1344,7 @@ public class LogicalPlanner extends 
BaseAlgebraVisitor<LogicalPlanner.PlanContex
     // Find expression which can be evaluated at this relation node.
     // Except for column references, additional expressions used in select 
list, where clause, order-by clauses
     // can be evaluated here. Their reference names are kept in 
newlyEvaluatedExprsRef.
-    Set<String> newlyEvaluatedExprsReferences = new LinkedHashSet<String>();
+    Set<String> newlyEvaluatedExprsReferences = new LinkedHashSet<>();
     for (Iterator<NamedExpr> iterator = 
block.namedExprsMgr.getIteratorForUnevaluatedExprs(); iterator.hasNext();) {
       NamedExpr rawTarget = iterator.next();
       try {

http://git-wip-us.apache.org/repos/asf/tajo/blob/aa699c70/tajo-plan/src/main/java/org/apache/tajo/plan/PlanString.java
----------------------------------------------------------------------
diff --git a/tajo-plan/src/main/java/org/apache/tajo/plan/PlanString.java 
b/tajo-plan/src/main/java/org/apache/tajo/plan/PlanString.java
index b06c68f..d80cb7e 100644
--- a/tajo-plan/src/main/java/org/apache/tajo/plan/PlanString.java
+++ b/tajo-plan/src/main/java/org/apache/tajo/plan/PlanString.java
@@ -27,8 +27,8 @@ import java.util.List;
 public class PlanString {
   final StringBuilder title;
 
-  final List<String> explanations = new ArrayList<String>();
-  final List<String> details = new ArrayList<String>();
+  final List<String> explanations = new ArrayList<>();
+  final List<String> details = new ArrayList<>();
 
   StringBuilder currentExplanation;
   StringBuilder currentDetail;

http://git-wip-us.apache.org/repos/asf/tajo/blob/aa699c70/tajo-plan/src/main/java/org/apache/tajo/plan/expr/AlgebraicUtil.java
----------------------------------------------------------------------
diff --git 
a/tajo-plan/src/main/java/org/apache/tajo/plan/expr/AlgebraicUtil.java 
b/tajo-plan/src/main/java/org/apache/tajo/plan/expr/AlgebraicUtil.java
index 19d5d16..734beb8 100644
--- a/tajo-plan/src/main/java/org/apache/tajo/plan/expr/AlgebraicUtil.java
+++ b/tajo-plan/src/main/java/org/apache/tajo/plan/expr/AlgebraicUtil.java
@@ -365,7 +365,7 @@ public class AlgebraicUtil {
    * @return An array of CNF-formed expressions
    */
   public static EvalNode [] toConjunctiveNormalFormArray(EvalNode expr) {
-    List<EvalNode> list = new ArrayList<EvalNode>();
+    List<EvalNode> list = new ArrayList<>();
     toConjunctiveNormalFormArrayRecursive(expr, list);
     return list.toArray(new EvalNode[list.size()]);
   }
@@ -412,7 +412,7 @@ public class AlgebraicUtil {
    * @return An array of CNF-formed expressions
    */
   public static EvalNode [] toDisjunctiveNormalFormArray(EvalNode...exprs) {
-    List<EvalNode> list = new ArrayList<EvalNode>();
+    List<EvalNode> list = new ArrayList<>();
     for (EvalNode expr : exprs) {
       toDisjunctiveNormalFormArrayRecursive(expr, list);
     }
@@ -437,7 +437,7 @@ public class AlgebraicUtil {
     }
 
     public String build() {
-      Stack<Expr> stack = new Stack<Expr>();
+      Stack<Expr> stack = new Stack<>();
       stack.push(expr);
       try {
         this.visit(null, stack, expr);

http://git-wip-us.apache.org/repos/asf/tajo/blob/aa699c70/tajo-plan/src/main/java/org/apache/tajo/plan/expr/CaseWhenEval.java
----------------------------------------------------------------------
diff --git 
a/tajo-plan/src/main/java/org/apache/tajo/plan/expr/CaseWhenEval.java 
b/tajo-plan/src/main/java/org/apache/tajo/plan/expr/CaseWhenEval.java
index 2f40974..331b8e1 100644
--- a/tajo-plan/src/main/java/org/apache/tajo/plan/expr/CaseWhenEval.java
+++ b/tajo-plan/src/main/java/org/apache/tajo/plan/expr/CaseWhenEval.java
@@ -158,7 +158,7 @@ public class CaseWhenEval extends EvalNode implements 
GsonObject {
   @Override
   public Object clone() throws CloneNotSupportedException {
     CaseWhenEval caseWhenEval = (CaseWhenEval) super.clone();
-    caseWhenEval.whens = new ArrayList<IfThenEval>();
+    caseWhenEval.whens = new ArrayList<>();
     for (IfThenEval ifThenEval : whens) {
       caseWhenEval.whens.add((IfThenEval) ifThenEval.clone());
     }

http://git-wip-us.apache.org/repos/asf/tajo/blob/aa699c70/tajo-plan/src/main/java/org/apache/tajo/plan/expr/EvalTreeUtil.java
----------------------------------------------------------------------
diff --git 
a/tajo-plan/src/main/java/org/apache/tajo/plan/expr/EvalTreeUtil.java 
b/tajo-plan/src/main/java/org/apache/tajo/plan/expr/EvalTreeUtil.java
index cf00534..fe1c373 100644
--- a/tajo-plan/src/main/java/org/apache/tajo/plan/expr/EvalTreeUtil.java
+++ b/tajo-plan/src/main/java/org/apache/tajo/plan/expr/EvalTreeUtil.java
@@ -408,7 +408,7 @@ public class EvalTreeUtil {
   }
   
   public static class AllColumnRefFinder implements EvalNodeVisitor {
-    private List<Column> colList = new ArrayList<Column>();
+    private List<Column> colList = new ArrayList<>();
     private FieldEval field = null;
     
     @Override

http://git-wip-us.apache.org/repos/asf/tajo/blob/aa699c70/tajo-plan/src/main/java/org/apache/tajo/plan/exprrewrite/rules/ConstantFolding.java
----------------------------------------------------------------------
diff --git 
a/tajo-plan/src/main/java/org/apache/tajo/plan/exprrewrite/rules/ConstantFolding.java
 
b/tajo-plan/src/main/java/org/apache/tajo/plan/exprrewrite/rules/ConstantFolding.java
index 37b77fd..63e921e 100644
--- 
a/tajo-plan/src/main/java/org/apache/tajo/plan/exprrewrite/rules/ConstantFolding.java
+++ 
b/tajo-plan/src/main/java/org/apache/tajo/plan/exprrewrite/rules/ConstantFolding.java
@@ -79,7 +79,7 @@ public class ConstantFolding extends 
SimpleEvalNodeVisitor<LogicalPlanner.PlanCo
   }
 
   // exceptional func names not to use constant folding
-  private static final Set<String> NON_CONSTANT_FUNC_NAMES = new 
HashSet<String>(Arrays.asList("sleep", "random"));
+  private static final Set<String> NON_CONSTANT_FUNC_NAMES = new 
HashSet<>(Arrays.asList("sleep", "random"));
 
   @Override
   public EvalNode visitFuncCall(LogicalPlanner.PlanContext context, 
FunctionEval evalNode, Stack<EvalNode> stack) {

http://git-wip-us.apache.org/repos/asf/tajo/blob/aa699c70/tajo-plan/src/main/java/org/apache/tajo/plan/joinorder/JoinGraphContext.java
----------------------------------------------------------------------
diff --git 
a/tajo-plan/src/main/java/org/apache/tajo/plan/joinorder/JoinGraphContext.java 
b/tajo-plan/src/main/java/org/apache/tajo/plan/joinorder/JoinGraphContext.java
index a3b529c..292e967 100644
--- 
a/tajo-plan/src/main/java/org/apache/tajo/plan/joinorder/JoinGraphContext.java
+++ 
b/tajo-plan/src/main/java/org/apache/tajo/plan/joinorder/JoinGraphContext.java
@@ -122,12 +122,12 @@ public class JoinGraphContext {
   }
 
   public JoinEdge cacheEdge(JoinEdge edge) {
-    edgeCache.put(new Pair<JoinVertex, JoinVertex>(edge.getLeftVertex(), 
edge.getRightVertex()), edge);
+    edgeCache.put(new Pair<>(edge.getLeftVertex(), edge.getRightVertex()), 
edge);
     return edge;
   }
 
   public JoinEdge getCachedOrNewJoinEdge(JoinSpec joinSpec, JoinVertex left, 
JoinVertex right) {
-    Pair<JoinVertex,JoinVertex> cacheKey = new Pair<JoinVertex, 
JoinVertex>(left, right);
+    Pair<JoinVertex,JoinVertex> cacheKey = new Pair<>(left, right);
     if (edgeCache.containsKey(cacheKey)) {
       return (JoinEdge) edgeCache.get(cacheKey);
     } else {

http://git-wip-us.apache.org/repos/asf/tajo/blob/aa699c70/tajo-plan/src/main/java/org/apache/tajo/plan/logical/DistinctGroupbyNode.java
----------------------------------------------------------------------
diff --git 
a/tajo-plan/src/main/java/org/apache/tajo/plan/logical/DistinctGroupbyNode.java 
b/tajo-plan/src/main/java/org/apache/tajo/plan/logical/DistinctGroupbyNode.java
index fb19f10..5ec0f02 100644
--- 
a/tajo-plan/src/main/java/org/apache/tajo/plan/logical/DistinctGroupbyNode.java
+++ 
b/tajo-plan/src/main/java/org/apache/tajo/plan/logical/DistinctGroupbyNode.java
@@ -122,7 +122,7 @@ public class DistinctGroupbyNode extends UnaryNode 
implements Projectable, Clone
     }
 
     if (subGroupbyPlan != null) {
-      cloneNode.subGroupbyPlan = new ArrayList<GroupbyNode>();
+      cloneNode.subGroupbyPlan = new ArrayList<>();
       for (GroupbyNode eachNode: subGroupbyPlan) {
         GroupbyNode groupbyNode = (GroupbyNode)eachNode.clone();
         groupbyNode.setPID(-1);
@@ -243,7 +243,7 @@ public class DistinctGroupbyNode extends UnaryNode 
implements Projectable, Clone
   }
 
   public Column[] getFirstStageShuffleKeyColumns() {
-    List<Column> shuffleKeyColumns = new ArrayList<Column>();
+    List<Column> shuffleKeyColumns = new ArrayList<>();
     shuffleKeyColumns.add(getOutSchema().getColumn(0));   //distinctseq column
     if (groupingColumns != null) {
       for (Column eachColumn: groupingColumns) {

http://git-wip-us.apache.org/repos/asf/tajo/blob/aa699c70/tajo-plan/src/main/java/org/apache/tajo/plan/logical/JoinSpec.java
----------------------------------------------------------------------
diff --git a/tajo-plan/src/main/java/org/apache/tajo/plan/logical/JoinSpec.java 
b/tajo-plan/src/main/java/org/apache/tajo/plan/logical/JoinSpec.java
index 7643e4b..abdafc7 100644
--- a/tajo-plan/src/main/java/org/apache/tajo/plan/logical/JoinSpec.java
+++ b/tajo-plan/src/main/java/org/apache/tajo/plan/logical/JoinSpec.java
@@ -39,7 +39,7 @@ public class JoinSpec implements Cloneable {
   }
 
   private JoinType type = null;
-  private Set<EvalNode> predicates = new TreeSet<EvalNode>(new 
EvalNodeComparator());
+  private Set<EvalNode> predicates = new TreeSet<>(new EvalNodeComparator());
 
   public JoinSpec() {
 

http://git-wip-us.apache.org/repos/asf/tajo/blob/aa699c70/tajo-plan/src/main/java/org/apache/tajo/plan/rewrite/BaseSchemaBuildPhase.java
----------------------------------------------------------------------
diff --git 
a/tajo-plan/src/main/java/org/apache/tajo/plan/rewrite/BaseSchemaBuildPhase.java
 
b/tajo-plan/src/main/java/org/apache/tajo/plan/rewrite/BaseSchemaBuildPhase.java
index f26e190..e41b7a7 100644
--- 
a/tajo-plan/src/main/java/org/apache/tajo/plan/rewrite/BaseSchemaBuildPhase.java
+++ 
b/tajo-plan/src/main/java/org/apache/tajo/plan/rewrite/BaseSchemaBuildPhase.java
@@ -177,7 +177,7 @@ public class BaseSchemaBuildPhase extends 
LogicalPlanPreprocessPhase {
     private static List<NamedExpr> resolveAsterisk(LogicalPlanner.PlanContext 
ctx, QualifiedAsteriskExpr asteriskExpr)
         throws TajoException {
       Column[] columns = getColumns(ctx, asteriskExpr);
-      List<NamedExpr> newTargetExprs = new 
ArrayList<NamedExpr>(columns.length);
+      List<NamedExpr> newTargetExprs = new ArrayList<>(columns.length);
       int i;
       for (i = 0; i < columns.length; i++) {
         newTargetExprs.add(new NamedExpr(new 
ColumnReferenceExpr(columns[i].getQualifier(), columns[i].getSimpleName())));

http://git-wip-us.apache.org/repos/asf/tajo/blob/aa699c70/tajo-plan/src/main/java/org/apache/tajo/plan/rewrite/rules/ProjectionPushDownRule.java
----------------------------------------------------------------------
diff --git 
a/tajo-plan/src/main/java/org/apache/tajo/plan/rewrite/rules/ProjectionPushDownRule.java
 
b/tajo-plan/src/main/java/org/apache/tajo/plan/rewrite/rules/ProjectionPushDownRule.java
index 408f2d2..abfc7a9 100644
--- 
a/tajo-plan/src/main/java/org/apache/tajo/plan/rewrite/rules/ProjectionPushDownRule.java
+++ 
b/tajo-plan/src/main/java/org/apache/tajo/plan/rewrite/rules/ProjectionPushDownRule.java
@@ -82,7 +82,7 @@ public class ProjectionPushDownRule extends
 
     LogicalPlan.QueryBlock topmostBlock = rootBlock;
 
-    Stack<LogicalNode> stack = new Stack<LogicalNode>();
+    Stack<LogicalNode> stack = new Stack<>();
     Context context = new Context(plan);
     visit(context, plan, topmostBlock, topmostBlock.getRoot(), stack);
 
@@ -406,17 +406,17 @@ public class ProjectionPushDownRule extends
     Set<String> requiredSet;
 
     public Context(LogicalPlan plan) {
-      requiredSet = new LinkedHashSet<String>();
+      requiredSet = new LinkedHashSet<>();
       targetListMgr = new TargetListManager(plan);
     }
 
     public Context(LogicalPlan plan, Collection<String> requiredSet) {
-      this.requiredSet = new LinkedHashSet<String>(requiredSet);
+      this.requiredSet = new LinkedHashSet<>(requiredSet);
       targetListMgr = new TargetListManager(plan);
     }
 
     public Context(Context upperContext) {
-      this.requiredSet = new LinkedHashSet<String>(upperContext.requiredSet);
+      this.requiredSet = new LinkedHashSet<>(upperContext.requiredSet);
       targetListMgr = upperContext.targetListMgr;
     }
 
@@ -567,7 +567,7 @@ public class ProjectionPushDownRule extends
     LogicalNode child = super.visitSort(newContext, plan, block, node, stack);
 
     // it rewrite sortkeys. This rewrite sets right column names and 
eliminates duplicated sort keys.
-    List<SortSpec> sortSpecs = new ArrayList<SortSpec>();
+    List<SortSpec> sortSpecs = new ArrayList<>();
     for (int i = 0; i < keyNames.length; i++) {
       String sortKey = keyNames[i];
       Target target = context.targetListMgr.getTarget(sortKey);
@@ -763,7 +763,7 @@ public class ProjectionPushDownRule extends
     List<Target> targets = Lists.newArrayList();
     if (groupingKeyNum > 0 && groupingKeyNames != null) {
       // Restoring grouping key columns
-      final List<Column> groupingColumns = new ArrayList<Column>();
+      final List<Column> groupingColumns = new ArrayList<>();
       for (String groupingKey : groupingKeyNames) {
         Target target = context.targetListMgr.getTarget(groupingKey);
 
@@ -1009,7 +1009,7 @@ public class ProjectionPushDownRule extends
 
     FilteredIterator(Target [] targets, Set<String> requiredReferences) {
       List<Target> filtered = TUtil.newList();
-      Map<String, Target> targetSet = new HashMap<String, Target>();
+      Map<String, Target> targetSet = new HashMap<>();
       for (Target t : targets) {
         // Only should keep an raw target instead of field reference.
         if (targetSet.containsKey(t.getCanonicalName())) {

http://git-wip-us.apache.org/repos/asf/tajo/blob/aa699c70/tajo-plan/src/main/java/org/apache/tajo/plan/util/PlannerUtil.java
----------------------------------------------------------------------
diff --git a/tajo-plan/src/main/java/org/apache/tajo/plan/util/PlannerUtil.java 
b/tajo-plan/src/main/java/org/apache/tajo/plan/util/PlannerUtil.java
index 7ba31bc..d722884 100644
--- a/tajo-plan/src/main/java/org/apache/tajo/plan/util/PlannerUtil.java
+++ b/tajo-plan/src/main/java/org/apache/tajo/plan/util/PlannerUtil.java
@@ -494,7 +494,7 @@ public class PlannerUtil {
   }
 
   private static class LogicalNodeFinder implements LogicalNodeVisitor {
-    private List<LogicalNode> list = new ArrayList<LogicalNode>();
+    private List<LogicalNode> list = new ArrayList<>();
     private final NodeType[] tofind;
     private boolean topmost = false;
     private boolean finished = false;
@@ -532,7 +532,7 @@ public class PlannerUtil {
   }
 
   private static class ParentNodeFinder implements LogicalNodeVisitor {
-    private List<LogicalNode> list = new ArrayList<LogicalNode>();
+    private List<LogicalNode> list = new ArrayList<>();
     private NodeType tofind;
 
     public ParentNodeFinder(NodeType type) {

http://git-wip-us.apache.org/repos/asf/tajo/blob/aa699c70/tajo-plan/src/main/java/org/apache/tajo/plan/visitor/ExplainLogicalPlanVisitor.java
----------------------------------------------------------------------
diff --git 
a/tajo-plan/src/main/java/org/apache/tajo/plan/visitor/ExplainLogicalPlanVisitor.java
 
b/tajo-plan/src/main/java/org/apache/tajo/plan/visitor/ExplainLogicalPlanVisitor.java
index f826479..23ff3dc 100644
--- 
a/tajo-plan/src/main/java/org/apache/tajo/plan/visitor/ExplainLogicalPlanVisitor.java
+++ 
b/tajo-plan/src/main/java/org/apache/tajo/plan/visitor/ExplainLogicalPlanVisitor.java
@@ -34,7 +34,7 @@ public class ExplainLogicalPlanVisitor extends 
BasicLogicalPlanVisitor<ExplainLo
   public static class Context {
     public int maxDepth  = -1;
     public int depth = 0;
-    public Stack<DepthString> explains = new Stack<DepthString>();
+    public Stack<DepthString> explains = new Stack<>();
 
     public void add(int depth, PlanString planString) {
       maxDepth = Math.max(maxDepth, depth);
@@ -69,7 +69,7 @@ public class ExplainLogicalPlanVisitor extends 
BasicLogicalPlanVisitor<ExplainLo
   }
 
   public Context getBlockPlanStrings(@Nullable LogicalPlan plan, LogicalNode 
node) throws TajoException {
-    Stack<LogicalNode> stack = new Stack<LogicalNode>();
+    Stack<LogicalNode> stack = new Stack<>();
     Context explainContext = new Context();
     visit(explainContext, plan, null, node, stack);
     return explainContext;

http://git-wip-us.apache.org/repos/asf/tajo/blob/aa699c70/tajo-pullserver/src/main/java/org/apache/tajo/pullserver/HttpDataServerHandler.java
----------------------------------------------------------------------
diff --git 
a/tajo-pullserver/src/main/java/org/apache/tajo/pullserver/HttpDataServerHandler.java
 
b/tajo-pullserver/src/main/java/org/apache/tajo/pullserver/HttpDataServerHandler.java
index 472b967..68e8093 100644
--- 
a/tajo-pullserver/src/main/java/org/apache/tajo/pullserver/HttpDataServerHandler.java
+++ 
b/tajo-pullserver/src/main/java/org/apache/tajo/pullserver/HttpDataServerHandler.java
@@ -47,7 +47,7 @@ public class HttpDataServerHandler extends 
SimpleChannelInboundHandler<FullHttpR
   private final static Log LOG = 
LogFactory.getLog(HttpDataServerHandler.class);
 
   Map<ExecutionBlockId, DataRetriever> retrievers =
-      new ConcurrentHashMap<ExecutionBlockId, DataRetriever>();
+          new ConcurrentHashMap<>();
   private String userName;
   private String appId;
 
@@ -219,7 +219,7 @@ public class HttpDataServerHandler extends 
SimpleChannelInboundHandler<FullHttpR
       return null;
     }
 
-    final List<String> ret = new ArrayList<String>();
+    final List<String> ret = new ArrayList<>();
     for (String qid : qids) {
       Collections.addAll(ret, qid.split(","));
     }

http://git-wip-us.apache.org/repos/asf/tajo/blob/aa699c70/tajo-pullserver/src/main/java/org/apache/tajo/pullserver/TajoPullServerService.java
----------------------------------------------------------------------
diff --git 
a/tajo-pullserver/src/main/java/org/apache/tajo/pullserver/TajoPullServerService.java
 
b/tajo-pullserver/src/main/java/org/apache/tajo/pullserver/TajoPullServerService.java
index d6f5a90..2eaa3d2 100644
--- 
a/tajo-pullserver/src/main/java/org/apache/tajo/pullserver/TajoPullServerService.java
+++ 
b/tajo-pullserver/src/main/java/org/apache/tajo/pullserver/TajoPullServerService.java
@@ -105,7 +105,7 @@ public class TajoPullServerService extends AbstractService {
   public static final String PULLSERVER_SERVICEID = "tajo.pullserver";
 
   private static final Map<String,String> userRsrc =
-    new ConcurrentHashMap<String,String>();
+          new ConcurrentHashMap<>();
   private String userName;
 
   public static final String SUFFLE_SSL_FILE_BUFFER_SIZE_KEY =
@@ -360,7 +360,7 @@ public class TajoPullServerService extends AbstractService {
   }
 
 
-  Map<String, ProcessingStatus> processingStatusMap = new 
ConcurrentHashMap<String, ProcessingStatus>();
+  Map<String, ProcessingStatus> processingStatusMap = new 
ConcurrentHashMap<>();
 
   public void completeFileChunk(FileRegion filePart,
                                    String requestUri,
@@ -763,7 +763,7 @@ public class TajoPullServerService extends AbstractService {
     if (null == mapq) {
       return null;
     }
-    final List<String> ret = new ArrayList<String>();
+    final List<String> ret = new ArrayList<>();
     for (String s : mapq) {
       Collections.addAll(ret, s.split(","));
     }

http://git-wip-us.apache.org/repos/asf/tajo/blob/aa699c70/tajo-pullserver/src/main/java/org/apache/tajo/pullserver/retriever/AdvancedDataRetriever.java
----------------------------------------------------------------------
diff --git 
a/tajo-pullserver/src/main/java/org/apache/tajo/pullserver/retriever/AdvancedDataRetriever.java
 
b/tajo-pullserver/src/main/java/org/apache/tajo/pullserver/retriever/AdvancedDataRetriever.java
index fb91094..59e8904 100644
--- 
a/tajo-pullserver/src/main/java/org/apache/tajo/pullserver/retriever/AdvancedDataRetriever.java
+++ 
b/tajo-pullserver/src/main/java/org/apache/tajo/pullserver/retriever/AdvancedDataRetriever.java
@@ -119,7 +119,7 @@ public class AdvancedDataRetriever implements DataRetriever 
{
       return null;
     }
 
-    final List<String> ret = new ArrayList<String>();
+    final List<String> ret = new ArrayList<>();
     for (String qid : qids) {
       Collections.addAll(ret, qid.split(","));
     }

http://git-wip-us.apache.org/repos/asf/tajo/blob/aa699c70/tajo-rpc/tajo-rpc-common/src/main/java/org/apache/tajo/rpc/NettyUtils.java
----------------------------------------------------------------------
diff --git 
a/tajo-rpc/tajo-rpc-common/src/main/java/org/apache/tajo/rpc/NettyUtils.java 
b/tajo-rpc/tajo-rpc-common/src/main/java/org/apache/tajo/rpc/NettyUtils.java
index 01fd48b..90b337a 100644
--- a/tajo-rpc/tajo-rpc-common/src/main/java/org/apache/tajo/rpc/NettyUtils.java
+++ b/tajo-rpc/tajo-rpc-common/src/main/java/org/apache/tajo/rpc/NettyUtils.java
@@ -44,7 +44,7 @@ public final class NettyUtils {
   }
 
   private static final Map<GROUP, EventLoopGroup> eventLoopGroupMap =
-      new ConcurrentHashMap<GROUP, EventLoopGroup>();
+          new ConcurrentHashMap<>();
 
   private NettyUtils(){
   }

http://git-wip-us.apache.org/repos/asf/tajo/blob/aa699c70/tajo-storage/tajo-storage-common/src/main/java/org/apache/tajo/storage/DiskDeviceInfo.java
----------------------------------------------------------------------
diff --git 
a/tajo-storage/tajo-storage-common/src/main/java/org/apache/tajo/storage/DiskDeviceInfo.java
 
b/tajo-storage/tajo-storage-common/src/main/java/org/apache/tajo/storage/DiskDeviceInfo.java
index 2396349..a058056 100644
--- 
a/tajo-storage/tajo-storage-common/src/main/java/org/apache/tajo/storage/DiskDeviceInfo.java
+++ 
b/tajo-storage/tajo-storage-common/src/main/java/org/apache/tajo/storage/DiskDeviceInfo.java
@@ -25,7 +25,7 @@ public class DiskDeviceInfo {
        private int id;
        private String name;
        
-       private List<DiskMountInfo> mountInfos = new ArrayList<DiskMountInfo>();
+       private List<DiskMountInfo> mountInfos = new ArrayList<>();
 
        public DiskDeviceInfo(int id) {
                this.id = id;

http://git-wip-us.apache.org/repos/asf/tajo/blob/aa699c70/tajo-storage/tajo-storage-common/src/main/java/org/apache/tajo/storage/DiskUtil.java
----------------------------------------------------------------------
diff --git 
a/tajo-storage/tajo-storage-common/src/main/java/org/apache/tajo/storage/DiskUtil.java
 
b/tajo-storage/tajo-storage-common/src/main/java/org/apache/tajo/storage/DiskUtil.java
index 19e08e8..7629d58 100644
--- 
a/tajo-storage/tajo-storage-common/src/main/java/org/apache/tajo/storage/DiskUtil.java
+++ 
b/tajo-storage/tajo-storage-common/src/main/java/org/apache/tajo/storage/DiskUtil.java
@@ -68,7 +68,7 @@ public class DiskUtil {
        }
 
        private static List<DiskDeviceInfo> getUnixDiskDeviceInfos() {
-               List<DiskDeviceInfo> infos = new ArrayList<DiskDeviceInfo>();
+               List<DiskDeviceInfo> infos = new ArrayList<>();
                
                File file = new File(UNIX_DISK_DEVICE_PATH);
                if(!file.exists()) {
@@ -82,7 +82,7 @@ public class DiskUtil {
                        String line = null;
                        
                        int count = 0;
-                       Set<String> deviceNames = new TreeSet<String>();
+                       Set<String> deviceNames = new TreeSet<>();
                        while((line = reader.readLine()) != null) {
                                if(count > 0 && !line.trim().isEmpty()) {
                                        String[] tokens = line.trim().split(" 
+");
@@ -137,7 +137,7 @@ public class DiskUtil {
                DiskDeviceInfo diskDeviceInfo = new DiskDeviceInfo(0);
                diskDeviceInfo.setName("default");
                
-               List<DiskDeviceInfo> infos = new ArrayList<DiskDeviceInfo>();
+               List<DiskDeviceInfo> infos = new ArrayList<>();
                
                infos.add(diskDeviceInfo);
                
@@ -146,7 +146,7 @@ public class DiskUtil {
        
        
        private static void setDeviceMountInfo(List<DiskDeviceInfo> 
deviceInfos) throws IOException {
-               Map<String, DiskDeviceInfo> deviceMap = new HashMap<String, 
DiskDeviceInfo>();
+               Map<String, DiskDeviceInfo> deviceMap = new HashMap<>();
                for(DiskDeviceInfo eachDevice: deviceInfos) {
                        deviceMap.put(eachDevice.getName(), eachDevice);
                }

http://git-wip-us.apache.org/repos/asf/tajo/blob/aa699c70/tajo-storage/tajo-storage-common/src/main/java/org/apache/tajo/storage/MergeScanner.java
----------------------------------------------------------------------
diff --git 
a/tajo-storage/tajo-storage-common/src/main/java/org/apache/tajo/storage/MergeScanner.java
 
b/tajo-storage/tajo-storage-common/src/main/java/org/apache/tajo/storage/MergeScanner.java
index b3b1edd..27ff589 100644
--- 
a/tajo-storage/tajo-storage-common/src/main/java/org/apache/tajo/storage/MergeScanner.java
+++ 
b/tajo-storage/tajo-storage-common/src/main/java/org/apache/tajo/storage/MergeScanner.java
@@ -64,7 +64,7 @@ public class MergeScanner implements Scanner {
     this.meta = meta;
     this.target = target;
 
-    this.fragments = new ArrayList<Fragment>();
+    this.fragments = new ArrayList<>();
 
     long numBytes = 0;
     for (Fragment eachFileFragment: rawFragmentList) {

http://git-wip-us.apache.org/repos/asf/tajo/blob/aa699c70/tajo-storage/tajo-storage-common/src/main/java/org/apache/tajo/storage/OldStorageManager.java
----------------------------------------------------------------------
diff --git 
a/tajo-storage/tajo-storage-common/src/main/java/org/apache/tajo/storage/OldStorageManager.java
 
b/tajo-storage/tajo-storage-common/src/main/java/org/apache/tajo/storage/OldStorageManager.java
index 2e00bc9..9716744 100644
--- 
a/tajo-storage/tajo-storage-common/src/main/java/org/apache/tajo/storage/OldStorageManager.java
+++ 
b/tajo-storage/tajo-storage-common/src/main/java/org/apache/tajo/storage/OldStorageManager.java
@@ -48,12 +48,12 @@ public class OldStorageManager {
    * Cache of scanner handlers for each storage type.
    */
   protected static final Map<String, Class<? extends Scanner>> 
SCANNER_HANDLER_CACHE
-      = new ConcurrentHashMap<String, Class<? extends Scanner>>();
+      = new ConcurrentHashMap<>();
   /**
    * Cache of appender handlers for each storage type.
    */
   protected static final Map<String, Class<? extends Appender>> 
APPENDER_HANDLER_CACHE
-      = new ConcurrentHashMap<String, Class<? extends Appender>>();
+      = new ConcurrentHashMap<>();
   private static final Class<?>[] DEFAULT_SCANNER_PARAMS = {
       Configuration.class,
       Schema.class,

http://git-wip-us.apache.org/repos/asf/tajo/blob/aa699c70/tajo-storage/tajo-storage-common/src/main/java/org/apache/tajo/storage/compress/CodecPool.java
----------------------------------------------------------------------
diff --git 
a/tajo-storage/tajo-storage-common/src/main/java/org/apache/tajo/storage/compress/CodecPool.java
 
b/tajo-storage/tajo-storage-common/src/main/java/org/apache/tajo/storage/compress/CodecPool.java
index baeda8c..6545e4e 100644
--- 
a/tajo-storage/tajo-storage-common/src/main/java/org/apache/tajo/storage/compress/CodecPool.java
+++ 
b/tajo-storage/tajo-storage-common/src/main/java/org/apache/tajo/storage/compress/CodecPool.java
@@ -43,14 +43,14 @@ public final class CodecPool {
    * construction/destruction of (possibly native) decompression codecs.
    */
   private static final Map<Class<Compressor>, List<Compressor>> 
COMPRESSOR_POOL =
-      new HashMap<Class<Compressor>, List<Compressor>>();
+          new HashMap<>();
 
   /**
    * A global decompressor pool used to save the expensive
    * construction/destruction of (possibly native) decompression codecs.
    */
   private static final Map<Class<Decompressor>, List<Decompressor>> 
DECOMPRESSOR_POOL =
-      new HashMap<Class<Decompressor>, List<Decompressor>>();
+          new HashMap<>();
 
   private static <T> T borrow(Map<Class<T>, List<T>> pool,
       Class<? extends T> codecClass) {

http://git-wip-us.apache.org/repos/asf/tajo/blob/aa699c70/tajo-storage/tajo-storage-common/src/test/java/org/apache/tajo/storage/TestTupleComparator.java
----------------------------------------------------------------------
diff --git 
a/tajo-storage/tajo-storage-common/src/test/java/org/apache/tajo/storage/TestTupleComparator.java
 
b/tajo-storage/tajo-storage-common/src/test/java/org/apache/tajo/storage/TestTupleComparator.java
index 9eec96f..521abf1 100644
--- 
a/tajo-storage/tajo-storage-common/src/test/java/org/apache/tajo/storage/TestTupleComparator.java
+++ 
b/tajo-storage/tajo-storage-common/src/test/java/org/apache/tajo/storage/TestTupleComparator.java
@@ -93,7 +93,7 @@ public class TestTupleComparator {
     tuple3.put(0, new Int4Datum(3));
     tuple3.put(1, new TextDatum("333"));
 
-    List<Tuple> tupleList = new ArrayList<Tuple>();
+    List<Tuple> tupleList = new ArrayList<>();
     tupleList.add(tuple1);
     tupleList.add(nullTuple);
     tupleList.add(tuple3);
@@ -133,7 +133,7 @@ public class TestTupleComparator {
     tuple3.put(0, new Int4Datum(3));
     tuple3.put(1, new TextDatum("333"));
 
-    List<Tuple> tupleList = new ArrayList<Tuple>();
+    List<Tuple> tupleList = new ArrayList<>();
     tupleList.add(tuple1);
     tupleList.add(nullTuple);
     tupleList.add(tuple3);

http://git-wip-us.apache.org/repos/asf/tajo/blob/aa699c70/tajo-storage/tajo-storage-hbase/src/main/java/org/apache/tajo/storage/hbase/AbstractHBaseAppender.java
----------------------------------------------------------------------
diff --git 
a/tajo-storage/tajo-storage-hbase/src/main/java/org/apache/tajo/storage/hbase/AbstractHBaseAppender.java
 
b/tajo-storage/tajo-storage-hbase/src/main/java/org/apache/tajo/storage/hbase/AbstractHBaseAppender.java
index af78d13..2e7db7f 100644
--- 
a/tajo-storage/tajo-storage-hbase/src/main/java/org/apache/tajo/storage/hbase/AbstractHBaseAppender.java
+++ 
b/tajo-storage/tajo-storage-hbase/src/main/java/org/apache/tajo/storage/hbase/AbstractHBaseAppender.java
@@ -102,7 +102,7 @@ public abstract class AbstractHBaseAppender implements 
Appender {
     mappingColumnFamilies = columnMapping.getMappingColumns();
 
     isRowKeyMappings = columnMapping.getIsRowKeyMappings();
-    List<Integer> rowkeyColumnIndexList = new ArrayList<Integer>();
+    List<Integer> rowkeyColumnIndexList = new ArrayList<>();
     for (int i = 0; i < isRowKeyMappings.length; i++) {
       if (isRowKeyMappings[i]) {
         rowkeyColumnIndexList.add(i);
@@ -122,7 +122,7 @@ public abstract class AbstractHBaseAppender implements 
Appender {
     columnKeyValueDataIndexes = new int[isColumnKeys.length];
     int index = 0;
     int numKeyValues = 0;
-    Map<String, Integer> cfNameIndexMap = new HashMap<String, Integer>();
+    Map<String, Integer> cfNameIndexMap = new HashMap<>();
     for (int i = 0; i < isColumnKeys.length; i++) {
       if (isRowKeyMappings[i]) {
         continue;

http://git-wip-us.apache.org/repos/asf/tajo/blob/aa699c70/tajo-storage/tajo-storage-hbase/src/main/java/org/apache/tajo/storage/hbase/ColumnMapping.java
----------------------------------------------------------------------
diff --git 
a/tajo-storage/tajo-storage-hbase/src/main/java/org/apache/tajo/storage/hbase/ColumnMapping.java
 
b/tajo-storage/tajo-storage-hbase/src/main/java/org/apache/tajo/storage/hbase/ColumnMapping.java
index 7df7e9c..be05d7c 100644
--- 
a/tajo-storage/tajo-storage-hbase/src/main/java/org/apache/tajo/storage/hbase/ColumnMapping.java
+++ 
b/tajo-storage/tajo-storage-hbase/src/main/java/org/apache/tajo/storage/hbase/ColumnMapping.java
@@ -170,7 +170,7 @@ public class ColumnMapping {
   }
 
   public List<String> getColumnFamilyNames() {
-    List<String> cfNames = new ArrayList<String>();
+    List<String> cfNames = new ArrayList<>();
 
     for (byte[][] eachCfName: mappingColumns) {
       if (eachCfName != null && eachCfName.length > 0 && eachCfName[0] != 
null) {

http://git-wip-us.apache.org/repos/asf/tajo/blob/aa699c70/tajo-storage/tajo-storage-hbase/src/main/java/org/apache/tajo/storage/hbase/HBaseTablespace.java
----------------------------------------------------------------------
diff --git 
a/tajo-storage/tajo-storage-hbase/src/main/java/org/apache/tajo/storage/hbase/HBaseTablespace.java
 
b/tajo-storage/tajo-storage-hbase/src/main/java/org/apache/tajo/storage/hbase/HBaseTablespace.java
index 0064be4..91840d4 100644
--- 
a/tajo-storage/tajo-storage-hbase/src/main/java/org/apache/tajo/storage/hbase/HBaseTablespace.java
+++ 
b/tajo-storage/tajo-storage-hbase/src/main/java/org/apache/tajo/storage/hbase/HBaseTablespace.java
@@ -79,7 +79,7 @@ public class HBaseTablespace extends Tablespace {
 
   private final static SortedInsertRewriter REWRITE_RULE = new 
SortedInsertRewriter();
 
-  private Map<HConnectionKey, HConnection> connMap = new 
HashMap<HConnectionKey, HConnection>();
+  private Map<HConnectionKey, HConnection> connMap = new HashMap<>();
 
   public HBaseTablespace(String spaceName, URI uri, JSONObject config) {
     super(spaceName, uri, config);
@@ -176,7 +176,7 @@ public class HBaseTablespace extends Tablespace {
               "External table should be a existed table.");
         }
         HTableDescriptor hTableDescriptor = 
hAdmin.getTableDescriptor(hTableName);
-        Set<String> tableColumnFamilies = new HashSet<String>();
+        Set<String> tableColumnFamilies = new HashSet<>();
         for (HColumnDescriptor eachColumn : 
hTableDescriptor.getColumnFamilies()) {
           tableColumnFamilies.add(eachColumn.getNameAsString());
         }
@@ -278,7 +278,7 @@ public class HBaseTablespace extends Tablespace {
             hbaseTableName);
       }
 
-      SortedSet<String> splitKeySet = new TreeSet<String>();
+      SortedSet<String> splitKeySet = new TreeSet<>();
       BufferedReader reader = null;
       try {
         reader = new BufferedReader(new InputStreamReader(fs.open(path)));
@@ -437,7 +437,7 @@ public class HBaseTablespace extends Tablespace {
         if (null == regLoc) {
           throw new IOException("Expecting at least one region.");
         }
-        List<Fragment> fragments = new ArrayList<Fragment>(1);
+        List<Fragment> fragments = new ArrayList<>(1);
         Fragment fragment = new HBaseFragment(
             tableDesc.getUri(),
             inputSourceId, htable.getName().getNameAsString(),
@@ -453,8 +453,8 @@ public class HBaseTablespace extends Tablespace {
 
       if (indexPredications != null && !indexPredications.isEmpty()) {
         // indexPredications is Disjunctive set
-        startRows = new ArrayList<byte[]>();
-        stopRows = new ArrayList<byte[]>();
+        startRows = new ArrayList<>();
+        stopRows = new ArrayList<>();
         for (IndexPredication indexPredication: indexPredications) {
           byte[] startRow;
           byte[] stopRow;
@@ -477,10 +477,10 @@ public class HBaseTablespace extends Tablespace {
       }
 
       hAdmin =  new HBaseAdmin(hbaseConf);
-      Map<ServerName, ServerLoad> serverLoadMap = new HashMap<ServerName, 
ServerLoad>();
+      Map<ServerName, ServerLoad> serverLoadMap = new HashMap<>();
 
       // region startkey -> HBaseFragment
-      Map<byte[], HBaseFragment> fragmentMap = new HashMap<byte[], 
HBaseFragment>();
+      Map<byte[], HBaseFragment> fragmentMap = new HashMap<>();
       for (int i = 0; i < keys.getFirst().length; i++) {
         HRegionLocation location = 
htable.getRegionLocation(keys.getFirst()[i], false);
 
@@ -549,7 +549,7 @@ public class HBaseTablespace extends Tablespace {
         }
       }
 
-      List<HBaseFragment> fragments = new 
ArrayList<HBaseFragment>(fragmentMap.values());
+      List<HBaseFragment> fragments = new ArrayList<>(fragmentMap.values());
       Collections.sort(fragments);
       if (!fragments.isEmpty()) {
         fragments.get(fragments.size() - 1).setLast(true);
@@ -622,7 +622,7 @@ public class HBaseTablespace extends Tablespace {
     private String username;
 
     HConnectionKey(Configuration conf) {
-      Map<String, String> m = new HashMap<String, String>();
+      Map<String, String> m = new HashMap<>();
       if (conf != null) {
         for (String property : CONNECTION_PROPERTIES) {
           String value = conf.get(property);
@@ -712,7 +712,7 @@ public class HBaseTablespace extends Tablespace {
                                                      @Nullable EvalNode 
filterCondition)
       throws IOException, MissingTablePropertyException, 
InvalidTablePropertyException {
 
-    List<IndexPredication> indexPredications = new 
ArrayList<IndexPredication>();
+    List<IndexPredication> indexPredications = new ArrayList<>();
     Column[] indexableColumns = getIndexableColumns(tableDesc);
     if (indexableColumns != null && indexableColumns.length == 1) {
       // Currently supports only single index column.
@@ -735,7 +735,7 @@ public class HBaseTablespace extends Tablespace {
 
   public List<Set<EvalNode>> findIndexablePredicateSet(@Nullable EvalNode qual,
                                                        Column[] 
indexableColumns) throws IOException {
-    List<Set<EvalNode>> indexablePredicateList = new 
ArrayList<Set<EvalNode>>();
+    List<Set<EvalNode>> indexablePredicateList = new ArrayList<>();
 
     // if a query statement has a search condition, try to find indexable 
predicates
     if (indexableColumns != null && qual != null) {
@@ -885,7 +885,7 @@ public class HBaseTablespace extends Tablespace {
           new String(new char[]{columnMapping.getRowKeyDelimiter(), 
Character.MAX_VALUE}));
     }
     if (startDatum != null || endDatum != null) {
-      return new Pair<Datum, Datum>(startDatum, endDatum);
+      return new Pair<>(startDatum, endDatum);
     } else {
       return null;
     }
@@ -955,7 +955,7 @@ public class HBaseTablespace extends Tablespace {
         if (endKeys.length == 1) {
           return new TupleRange[]{dataRange};
         }
-        List<TupleRange> tupleRanges = new 
ArrayList<TupleRange>(endKeys.length);
+        List<TupleRange> tupleRanges = new ArrayList<>(endKeys.length);
 
         TupleComparator comparator = new BaseTupleComparator(inputSchema, 
sortSpecs);
         Tuple previousTuple = dataRange.getStart();

http://git-wip-us.apache.org/repos/asf/tajo/blob/aa699c70/tajo-storage/tajo-storage-hbase/src/main/java/org/apache/tajo/storage/hbase/HFileAppender.java
----------------------------------------------------------------------
diff --git 
a/tajo-storage/tajo-storage-hbase/src/main/java/org/apache/tajo/storage/hbase/HFileAppender.java
 
b/tajo-storage/tajo-storage-hbase/src/main/java/org/apache/tajo/storage/hbase/HFileAppender.java
index 36678e4..42f25cc 100644
--- 
a/tajo-storage/tajo-storage-hbase/src/main/java/org/apache/tajo/storage/hbase/HFileAppender.java
+++ 
b/tajo-storage/tajo-storage-hbase/src/main/java/org/apache/tajo/storage/hbase/HFileAppender.java
@@ -87,7 +87,7 @@ public class HFileAppender extends AbstractHBaseAppender {
   long totalNumBytes = 0;
   ImmutableBytesWritable keyWritable = new ImmutableBytesWritable();
   boolean first = true;
-  TreeSet<KeyValue> kvSet = new TreeSet<KeyValue>(KeyValue.COMPARATOR);
+  TreeSet<KeyValue> kvSet = new TreeSet<>(KeyValue.COMPARATOR);
 
 
   @Override

http://git-wip-us.apache.org/repos/asf/tajo/blob/aa699c70/tajo-storage/tajo-storage-hbase/src/main/java/org/apache/tajo/storage/hbase/SortedInsertRewriter.java
----------------------------------------------------------------------
diff --git 
a/tajo-storage/tajo-storage-hbase/src/main/java/org/apache/tajo/storage/hbase/SortedInsertRewriter.java
 
b/tajo-storage/tajo-storage-hbase/src/main/java/org/apache/tajo/storage/hbase/SortedInsertRewriter.java
index a99d4d0..5c418df 100644
--- 
a/tajo-storage/tajo-storage-hbase/src/main/java/org/apache/tajo/storage/hbase/SortedInsertRewriter.java
+++ 
b/tajo-storage/tajo-storage-hbase/src/main/java/org/apache/tajo/storage/hbase/SortedInsertRewriter.java
@@ -58,7 +58,7 @@ public class SortedInsertRewriter implements 
LogicalPlanRewriteRule {
   public static Column[] getIndexColumns(Schema tableSchema, KeyValueSet 
tableProperty)
       throws IOException, TajoException {
 
-    List<Column> indexColumns = new ArrayList<Column>();
+    List<Column> indexColumns = new ArrayList<>();
 
     ColumnMapping columnMapping = new ColumnMapping(tableSchema, 
tableProperty);
 

http://git-wip-us.apache.org/repos/asf/tajo/blob/aa699c70/tajo-storage/tajo-storage-hdfs/src/main/java/org/apache/tajo/storage/FileTablespace.java
----------------------------------------------------------------------
diff --git 
a/tajo-storage/tajo-storage-hdfs/src/main/java/org/apache/tajo/storage/FileTablespace.java
 
b/tajo-storage/tajo-storage-hdfs/src/main/java/org/apache/tajo/storage/FileTablespace.java
index 1b0952e..6ba2029 100644
--- 
a/tajo-storage/tajo-storage-hdfs/src/main/java/org/apache/tajo/storage/FileTablespace.java
+++ 
b/tajo-storage/tajo-storage-hdfs/src/main/java/org/apache/tajo/storage/FileTablespace.java
@@ -204,7 +204,7 @@ public class FileTablespace extends Tablespace {
     FileSystem fs = tablePath.getFileSystem(conf);
 
     long defaultBlockSize = size;
-    List<FileFragment> listTablets = new ArrayList<FileFragment>();
+    List<FileFragment> listTablets = new ArrayList<>();
     FileFragment tablet;
 
     FileStatus[] fileLists = fs.listStatus(tablePath);
@@ -236,7 +236,7 @@ public class FileTablespace extends Tablespace {
     FileSystem fs = tablePath.getFileSystem(conf);
 
     long defaultBlockSize = size;
-    List<FileFragment> listTablets = new ArrayList<FileFragment>();
+    List<FileFragment> listTablets = new ArrayList<>();
     FileFragment tablet;
 
     FileStatus[] fileLists = fs.listStatus(tablePath);
@@ -324,16 +324,16 @@ public class FileTablespace extends Tablespace {
    * @throws IOException if zero items.
    */
   protected List<FileStatus> listStatus(Path... dirs) throws IOException {
-    List<FileStatus> result = new ArrayList<FileStatus>();
+    List<FileStatus> result = new ArrayList<>();
     if (dirs.length == 0) {
       throw new IOException("No input paths specified in job");
     }
 
-    List<IOException> errors = new ArrayList<IOException>();
+    List<IOException> errors = new ArrayList<>();
 
     // creates a MultiPathFilter with the hiddenFileFilter and the
     // user provided one (if any).
-    List<PathFilter> filters = new ArrayList<PathFilter>();
+    List<PathFilter> filters = new ArrayList<>();
     filters.add(hiddenFileFilter);
 
     PathFilter inputFilter = new MultiPathFilter(filters);
@@ -426,7 +426,7 @@ public class FileTablespace extends Tablespace {
   protected FileFragment makeNonSplit(String fragmentId, Path file, long 
start, long length,
                                       BlockLocation[] blkLocations) throws 
IOException {
 
-    Map<String, Integer> hostsBlockMap = new HashMap<String, Integer>();
+    Map<String, Integer> hostsBlockMap = new HashMap<>();
     for (BlockLocation blockLocation : blkLocations) {
       for (String host : blockLocation.getHosts()) {
         if (hostsBlockMap.containsKey(host)) {
@@ -437,7 +437,7 @@ public class FileTablespace extends Tablespace {
       }
     }
 
-    List<Map.Entry<String, Integer>> entries = new ArrayList<Map.Entry<String, 
Integer>>(hostsBlockMap.entrySet());
+    List<Map.Entry<String, Integer>> entries = new 
ArrayList<>(hostsBlockMap.entrySet());
     Collections.sort(entries, new Comparator<Map.Entry<String, Integer>>() {
 
       @Override

http://git-wip-us.apache.org/repos/asf/tajo/blob/aa699c70/tajo-storage/tajo-storage-hdfs/src/main/java/org/apache/tajo/storage/HashShuffleAppender.java
----------------------------------------------------------------------
diff --git 
a/tajo-storage/tajo-storage-hdfs/src/main/java/org/apache/tajo/storage/HashShuffleAppender.java
 
b/tajo-storage/tajo-storage-hdfs/src/main/java/org/apache/tajo/storage/HashShuffleAppender.java
index 4c772c9..a1eead2 100644
--- 
a/tajo-storage/tajo-storage-hdfs/src/main/java/org/apache/tajo/storage/HashShuffleAppender.java
+++ 
b/tajo-storage/tajo-storage-hdfs/src/main/java/org/apache/tajo/storage/HashShuffleAppender.java
@@ -45,7 +45,7 @@ public class HashShuffleAppender implements Appender {
   private Map<TaskAttemptId, List<Pair<Long, Pair<Integer, Integer>>>> 
taskTupleIndexes;
 
   //page start offset, length
-  private List<Pair<Long, Integer>> pages = new ArrayList<Pair<Long, 
Integer>>();
+  private List<Pair<Long, Integer>> pages = new ArrayList<>();
 
   private Pair<Long, Integer> currentPage;
 
@@ -69,7 +69,7 @@ public class HashShuffleAppender implements Appender {
   @Override
   public void init() throws IOException {
     currentPage = new Pair(0L, 0);
-    taskTupleIndexes = new HashMap<TaskAttemptId, List<Pair<Long, 
Pair<Integer, Integer>>>>();
+    taskTupleIndexes = new HashMap<>();
     rowNumInPage = 0;
   }
 
@@ -98,7 +98,7 @@ public class HashShuffleAppender implements Appender {
       int nextRowNum = rowNumInPage + tuples.size();
       List<Pair<Long, Pair<Integer, Integer>>> taskIndexes = 
taskTupleIndexes.get(taskId);
       if (taskIndexes == null) {
-        taskIndexes = new ArrayList<Pair<Long, Pair<Integer, Integer>>>();
+        taskIndexes = new ArrayList<>();
         taskTupleIndexes.put(taskId, taskIndexes);
       }
       taskIndexes.add(
@@ -194,7 +194,7 @@ public class HashShuffleAppender implements Appender {
   }
 
   public List<Pair<Long, Pair<Integer, Integer>>> getMergedTupleIndexes() {
-    List<Pair<Long, Pair<Integer, Integer>>> merged = new ArrayList<Pair<Long, 
Pair<Integer, Integer>>>();
+    List<Pair<Long, Pair<Integer, Integer>>> merged = new ArrayList<>();
 
     for (List<Pair<Long, Pair<Integer, Integer>>> eachFailureIndex: 
taskTupleIndexes.values()) {
       merged.addAll(eachFailureIndex);

http://git-wip-us.apache.org/repos/asf/tajo/blob/aa699c70/tajo-storage/tajo-storage-hdfs/src/main/java/org/apache/tajo/storage/HashShuffleAppenderManager.java
----------------------------------------------------------------------
diff --git 
a/tajo-storage/tajo-storage-hdfs/src/main/java/org/apache/tajo/storage/HashShuffleAppenderManager.java
 
b/tajo-storage/tajo-storage-hdfs/src/main/java/org/apache/tajo/storage/HashShuffleAppenderManager.java
index b118044..4297e4d 100644
--- 
a/tajo-storage/tajo-storage-hdfs/src/main/java/org/apache/tajo/storage/HashShuffleAppenderManager.java
+++ 
b/tajo-storage/tajo-storage-hdfs/src/main/java/org/apache/tajo/storage/HashShuffleAppenderManager.java
@@ -43,7 +43,7 @@ public class HashShuffleAppenderManager {
   private static final Log LOG = 
LogFactory.getLog(HashShuffleAppenderManager.class);
 
   private Map<ExecutionBlockId, Map<Integer, PartitionAppenderMeta>> 
appenderMap =
-      new ConcurrentHashMap<ExecutionBlockId, Map<Integer, 
PartitionAppenderMeta>>();
+          new ConcurrentHashMap<>();
   private TajoConf systemConf;
   private FileSystem defaultFS;
   private FileSystem localFS;
@@ -68,7 +68,7 @@ public class HashShuffleAppenderManager {
       Map<Integer, PartitionAppenderMeta> partitionAppenderMap = 
appenderMap.get(ebId);
 
       if (partitionAppenderMap == null) {
-        partitionAppenderMap = new ConcurrentHashMap<Integer, 
PartitionAppenderMeta>();
+        partitionAppenderMap = new ConcurrentHashMap<>();
         appenderMap.put(ebId, partitionAppenderMap);
       }
 
@@ -137,7 +137,7 @@ public class HashShuffleAppenderManager {
     }
 
     // Send Intermediate data to QueryMaster.
-    List<HashShuffleIntermediate> intermediateEntries = new 
ArrayList<HashShuffleIntermediate>();
+    List<HashShuffleIntermediate> intermediateEntries = new ArrayList<>();
     for (PartitionAppenderMeta eachMeta : partitionAppenderMap.values()) {
       try {
         eachMeta.appender.close();
@@ -180,7 +180,7 @@ public class HashShuffleAppenderManager {
     private Collection<Pair<Long, Pair<Integer, Integer>>> 
failureTskTupleIndexes;
 
     //[<page start offset, length>]
-    private List<Pair<Long, Integer>> pages = new ArrayList<Pair<Long, 
Integer>>();
+    private List<Pair<Long, Integer>> pages = new ArrayList<>();
 
     public HashShuffleIntermediate(int partId, long volume,
                                    List<Pair<Long, Integer>> pages,

http://git-wip-us.apache.org/repos/asf/tajo/blob/aa699c70/tajo-storage/tajo-storage-hdfs/src/main/java/org/apache/tajo/storage/avro/AvroAppender.java
----------------------------------------------------------------------
diff --git 
a/tajo-storage/tajo-storage-hdfs/src/main/java/org/apache/tajo/storage/avro/AvroAppender.java
 
b/tajo-storage/tajo-storage-hdfs/src/main/java/org/apache/tajo/storage/avro/AvroAppender.java
index 0c67320..ff0e8c0 100644
--- 
a/tajo-storage/tajo-storage-hdfs/src/main/java/org/apache/tajo/storage/avro/AvroAppender.java
+++ 
b/tajo-storage/tajo-storage-hdfs/src/main/java/org/apache/tajo/storage/avro/AvroAppender.java
@@ -80,8 +80,8 @@ public class AvroAppender extends FileAppender {
     avroFields = avroSchema.getFields();
 
     DatumWriter<GenericRecord> datumWriter =
-        new GenericDatumWriter<GenericRecord>(avroSchema);
-    dataFileWriter = new DataFileWriter<GenericRecord>(datumWriter);
+            new GenericDatumWriter<>(avroSchema);
+    dataFileWriter = new DataFileWriter<>(datumWriter);
     dataFileWriter.create(avroSchema, outputStream);
 
     if (enabledStats) {

http://git-wip-us.apache.org/repos/asf/tajo/blob/aa699c70/tajo-storage/tajo-storage-hdfs/src/main/java/org/apache/tajo/storage/avro/AvroScanner.java
----------------------------------------------------------------------
diff --git 
a/tajo-storage/tajo-storage-hdfs/src/main/java/org/apache/tajo/storage/avro/AvroScanner.java
 
b/tajo-storage/tajo-storage-hdfs/src/main/java/org/apache/tajo/storage/avro/AvroScanner.java
index 5946e08..afa2701 100644
--- 
a/tajo-storage/tajo-storage-hdfs/src/main/java/org/apache/tajo/storage/avro/AvroScanner.java
+++ 
b/tajo-storage/tajo-storage-hdfs/src/main/java/org/apache/tajo/storage/avro/AvroScanner.java
@@ -85,9 +85,9 @@ public class AvroScanner extends FileScanner {
     avroSchema = AvroUtil.getAvroSchema(meta, conf);
     avroFields = avroSchema.getFields();
 
-    DatumReader<GenericRecord> datumReader = new 
GenericDatumReader<GenericRecord>(avroSchema);
+    DatumReader<GenericRecord> datumReader = new 
GenericDatumReader<>(avroSchema);
     SeekableInput input = new FsInput(fragment.getPath(), conf);
-    dataFileReader = new DataFileReader<GenericRecord>(input, datumReader);
+    dataFileReader = new DataFileReader<>(input, datumReader);
     super.init();
   }
 

http://git-wip-us.apache.org/repos/asf/tajo/blob/aa699c70/tajo-storage/tajo-storage-hdfs/src/main/java/org/apache/tajo/storage/fragment/FileFragment.java
----------------------------------------------------------------------
diff --git 
a/tajo-storage/tajo-storage-hdfs/src/main/java/org/apache/tajo/storage/fragment/FileFragment.java
 
b/tajo-storage/tajo-storage-hdfs/src/main/java/org/apache/tajo/storage/fragment/FileFragment.java
index 5f94aae..6ac5fc3 100644
--- 
a/tajo-storage/tajo-storage-hdfs/src/main/java/org/apache/tajo/storage/fragment/FileFragment.java
+++ 
b/tajo-storage/tajo-storage-hdfs/src/main/java/org/apache/tajo/storage/fragment/FileFragment.java
@@ -217,7 +217,7 @@ public class FileFragment implements Fragment, 
Comparable<FileFragment>, Cloneab
     builder.setLength(this.length);
     builder.setPath(this.uri.toString());
     if(diskIds != null) {
-      List<Integer> idList = new ArrayList<Integer>();
+      List<Integer> idList = new ArrayList<>();
       for(int eachId: diskIds) {
         idList.add(eachId);
       }

http://git-wip-us.apache.org/repos/asf/tajo/blob/aa699c70/tajo-storage/tajo-storage-hdfs/src/main/java/org/apache/tajo/storage/index/bst/BSTIndex.java
----------------------------------------------------------------------
diff --git 
a/tajo-storage/tajo-storage-hdfs/src/main/java/org/apache/tajo/storage/index/bst/BSTIndex.java
 
b/tajo-storage/tajo-storage-hdfs/src/main/java/org/apache/tajo/storage/index/bst/BSTIndex.java
index ba81c3e..3affd50 100644
--- 
a/tajo-storage/tajo-storage-hdfs/src/main/java/org/apache/tajo/storage/index/bst/BSTIndex.java
+++ 
b/tajo-storage/tajo-storage-hdfs/src/main/java/org/apache/tajo/storage/index/bst/BSTIndex.java
@@ -256,14 +256,14 @@ public class BSTIndex implements IndexMethod {
       private TreeMap<Tuple, LinkedList<Long>> map;
 
       public KeyOffsetCollector(TupleComparator comparator) {
-        map = new TreeMap<Tuple, LinkedList<Long>>(comparator);
+        map = new TreeMap<>(comparator);
       }
 
       public void put(final Tuple key, final long offset) {
         if (map.containsKey(key)) {
           map.get(key).add(offset);
         } else {
-          LinkedList<Long> list = new LinkedList<Long>();
+          LinkedList<Long> list = new LinkedList<>();
           list.add(offset);
           map.put(key, list);
         }

http://git-wip-us.apache.org/repos/asf/tajo/blob/aa699c70/tajo-storage/tajo-storage-hdfs/src/main/java/org/apache/tajo/storage/orc/ORCScanner.java
----------------------------------------------------------------------
diff --git 
a/tajo-storage/tajo-storage-hdfs/src/main/java/org/apache/tajo/storage/orc/ORCScanner.java
 
b/tajo-storage/tajo-storage-hdfs/src/main/java/org/apache/tajo/storage/orc/ORCScanner.java
index 8a9d623..b8b75ed 100644
--- 
a/tajo-storage/tajo-storage-hdfs/src/main/java/org/apache/tajo/storage/orc/ORCScanner.java
+++ 
b/tajo-storage/tajo-storage-hdfs/src/main/java/org/apache/tajo/storage/orc/ORCScanner.java
@@ -148,7 +148,7 @@ public class ORCScanner extends FileScanner {
       vectors[i] = createOrcVector(targetColInfo[i].type);
     }
 
-    Set<Integer> columnSet = new HashSet<Integer>();
+    Set<Integer> columnSet = new HashSet<>();
     for (ColumnInfo colInfo: targetColInfo) {
       columnSet.add(colInfo.id);
     }

http://git-wip-us.apache.org/repos/asf/tajo/blob/aa699c70/tajo-storage/tajo-storage-hdfs/src/main/java/org/apache/tajo/storage/orc/objectinspector/TajoStructObjectInspector.java
----------------------------------------------------------------------
diff --git 
a/tajo-storage/tajo-storage-hdfs/src/main/java/org/apache/tajo/storage/orc/objectinspector/TajoStructObjectInspector.java
 
b/tajo-storage/tajo-storage-hdfs/src/main/java/org/apache/tajo/storage/orc/objectinspector/TajoStructObjectInspector.java
index a8b4b49..f28989b 100644
--- 
a/tajo-storage/tajo-storage-hdfs/src/main/java/org/apache/tajo/storage/orc/objectinspector/TajoStructObjectInspector.java
+++ 
b/tajo-storage/tajo-storage-hdfs/src/main/java/org/apache/tajo/storage/orc/objectinspector/TajoStructObjectInspector.java
@@ -69,7 +69,7 @@ public class TajoStructObjectInspector extends 
StructObjectInspector {
   }
 
   TajoStructObjectInspector(Schema schema) {
-    structFields = new ArrayList<TajoStructField>(schema.size());
+    structFields = new ArrayList<>(schema.size());
 
     for (Column c: schema.getRootColumns()) {
       try {

http://git-wip-us.apache.org/repos/asf/tajo/blob/aa699c70/tajo-storage/tajo-storage-hdfs/src/main/java/org/apache/tajo/storage/parquet/TajoSchemaConverter.java
----------------------------------------------------------------------
diff --git 
a/tajo-storage/tajo-storage-hdfs/src/main/java/org/apache/tajo/storage/parquet/TajoSchemaConverter.java
 
b/tajo-storage/tajo-storage-hdfs/src/main/java/org/apache/tajo/storage/parquet/TajoSchemaConverter.java
index 555b623..e4f4730 100644
--- 
a/tajo-storage/tajo-storage-hdfs/src/main/java/org/apache/tajo/storage/parquet/TajoSchemaConverter.java
+++ 
b/tajo-storage/tajo-storage-hdfs/src/main/java/org/apache/tajo/storage/parquet/TajoSchemaConverter.java
@@ -54,7 +54,7 @@ public class TajoSchemaConverter {
   }
 
   private Schema convertFields(List<Type> parquetFields) {
-    List<Column> columns = new ArrayList<Column>();
+    List<Column> columns = new ArrayList<>();
     for (int i = 0; i < parquetFields.size(); ++i) {
       Type fieldType = parquetFields.get(i);
       if (fieldType.isRepetition(Type.Repetition.REPEATED)) {
@@ -141,7 +141,7 @@ public class TajoSchemaConverter {
    * @return The resulting Parquet schema.
    */
   public MessageType convert(Schema tajoSchema) {
-    List<Type> types = new ArrayList<Type>();
+    List<Type> types = new ArrayList<>();
     for (int i = 0; i < tajoSchema.size(); ++i) {
       Column column = tajoSchema.getColumn(i);
       if (column.getDataType().getType() == TajoDataTypes.Type.NULL_TYPE) {

http://git-wip-us.apache.org/repos/asf/tajo/blob/aa699c70/tajo-storage/tajo-storage-hdfs/src/main/java/org/apache/tajo/storage/parquet/TajoWriteSupport.java
----------------------------------------------------------------------
diff --git 
a/tajo-storage/tajo-storage-hdfs/src/main/java/org/apache/tajo/storage/parquet/TajoWriteSupport.java
 
b/tajo-storage/tajo-storage-hdfs/src/main/java/org/apache/tajo/storage/parquet/TajoWriteSupport.java
index de2a1e3..acb9015 100644
--- 
a/tajo-storage/tajo-storage-hdfs/src/main/java/org/apache/tajo/storage/parquet/TajoWriteSupport.java
+++ 
b/tajo-storage/tajo-storage-hdfs/src/main/java/org/apache/tajo/storage/parquet/TajoWriteSupport.java
@@ -62,7 +62,7 @@ public class TajoWriteSupport extends WriteSupport<Tuple> {
    */
   @Override
   public WriteContext init(Configuration configuration) {
-    Map<String, String> extraMetaData = new HashMap<String, String>();
+    Map<String, String> extraMetaData = new HashMap<>();
     return new WriteContext(rootSchema, extraMetaData);
   }
 

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