Author: tn
Date: Thu Dec 13 21:52:42 2012
New Revision: 1421567
URL: http://svn.apache.org/viewvc?rev=1421567&view=rev
Log:
[COLLECTION-436] Added emptyIfNull methods to [Collection,Set,List,Map]Utils.
Thanks to Arman Sharif for report and patch.
Modified:
commons/proper/collections/trunk/src/changes/changes.xml
commons/proper/collections/trunk/src/main/java/org/apache/commons/collections/CollectionUtils.java
commons/proper/collections/trunk/src/main/java/org/apache/commons/collections/ListUtils.java
commons/proper/collections/trunk/src/main/java/org/apache/commons/collections/MapUtils.java
commons/proper/collections/trunk/src/main/java/org/apache/commons/collections/SetUtils.java
commons/proper/collections/trunk/src/test/java/org/apache/commons/collections/CollectionUtilsTest.java
commons/proper/collections/trunk/src/test/java/org/apache/commons/collections/ListUtilsTest.java
commons/proper/collections/trunk/src/test/java/org/apache/commons/collections/MapUtilsTest.java
commons/proper/collections/trunk/src/test/java/org/apache/commons/collections/SetUtilsTest.java
Modified: commons/proper/collections/trunk/src/changes/changes.xml
URL:
http://svn.apache.org/viewvc/commons/proper/collections/trunk/src/changes/changes.xml?rev=1421567&r1=1421566&r2=1421567&view=diff
==============================================================================
--- commons/proper/collections/trunk/src/changes/changes.xml (original)
+++ commons/proper/collections/trunk/src/changes/changes.xml Thu Dec 13
21:52:42 2012
@@ -22,6 +22,10 @@
<body>
<release version="4.0" date="TBA" description="Next release">
+ <action issue="COLLECTIONS-436" dev="tn" type="add" due-to="Arman Sharif">
+ Added "emptyIfNull" methods to classes "CollectionUtils", "ListUtils",
"SetUtils"
+ and "MapUtils".
+ </action>
<action issue="COLLECTIONS-415" dev="tn" type="add" due-to="Adrian Nistor">
Added clarifying javadoc wrt runtime complexity of
"AbstrictLinkedList#removeAll".
</action>
Modified:
commons/proper/collections/trunk/src/main/java/org/apache/commons/collections/CollectionUtils.java
URL:
http://svn.apache.org/viewvc/commons/proper/collections/trunk/src/main/java/org/apache/commons/collections/CollectionUtils.java?rev=1421567&r1=1421566&r2=1421567&view=diff
==============================================================================
---
commons/proper/collections/trunk/src/main/java/org/apache/commons/collections/CollectionUtils.java
(original)
+++
commons/proper/collections/trunk/src/main/java/org/apache/commons/collections/CollectionUtils.java
Thu Dec 13 21:52:42 2012
@@ -115,7 +115,8 @@ public class CollectionUtils {
* undesirable. This implementation only implements Collection.
*/
@SuppressWarnings("rawtypes") // we deliberately use the raw type here
- public static final Collection EMPTY_COLLECTION =
UnmodifiableCollection.unmodifiableCollection(new ArrayList<Object>());
+ public static final Collection EMPTY_COLLECTION =
+ UnmodifiableCollection.unmodifiableCollection(new ArrayList<Object>());
/**
* <code>CollectionUtils</code> should not normally be instantiated.
@@ -128,6 +129,7 @@ public class CollectionUtils {
*
* @see #EMPTY_COLLECTION
* @since 4.0
+ * @param <T> the element type
* @return immutable empty collection
*/
@SuppressWarnings("unchecked")
@@ -136,6 +138,19 @@ public class CollectionUtils {
}
/**
+ * Returns an immutable empty collection if the argument is
<code>null</code>,
+ * or the argument itself otherwise.
+ *
+ * @param <T> the element type
+ * @param collection the collection, possibly <code>null</code>
+ * @return an empty collection if the argument is <code>null</code>
+ */
+ @SuppressWarnings("unchecked")
+ public static <T> Collection<T> emptyIfNull(Collection<T> collection) {
+ return collection == null ? EMPTY_COLLECTION : collection;
+ }
+
+ /**
* Returns a {@link Collection} containing the union of the given
* {@link Collection}s.
* <p>
@@ -188,7 +203,8 @@ public class CollectionUtils {
* <p>
* The cardinality of each element <i>e</i> in the returned
* {@link Collection} will be equal to
- * <tt>max(cardinality(<i>e</i>,<i>a</i>),cardinality(<i>e</i>,<i>b</i>))
- min(cardinality(<i>e</i>,<i>a</i>),cardinality(<i>e</i>,<i>b</i>))</tt>.
+ * <tt>max(cardinality(<i>e</i>,<i>a</i>),cardinality(<i>e</i>,<i>b</i>))
- min(cardinality(<i>e</i>,<i>a</i>),
+ * cardinality(<i>e</i>,<i>b</i>))</tt>.
* <p>
* This is equivalent to
* <tt>{@link #subtract subtract}({@link #union union(a,b)},{@link
#intersection intersection(a,b)})</tt>
Modified:
commons/proper/collections/trunk/src/main/java/org/apache/commons/collections/ListUtils.java
URL:
http://svn.apache.org/viewvc/commons/proper/collections/trunk/src/main/java/org/apache/commons/collections/ListUtils.java?rev=1421567&r1=1421566&r2=1421567&view=diff
==============================================================================
---
commons/proper/collections/trunk/src/main/java/org/apache/commons/collections/ListUtils.java
(original)
+++
commons/proper/collections/trunk/src/main/java/org/apache/commons/collections/ListUtils.java
Thu Dec 13 21:52:42 2012
@@ -54,6 +54,19 @@ public class ListUtils {
}
//-----------------------------------------------------------------------
+
+ /**
+ * Returns an immutable empty list if the argument is <code>null</code>,
+ * or the argument itself otherwise.
+ *
+ * @param <T> the element type
+ * @param list the list, possibly <code>null</code>
+ * @return an empty list if the argument is <code>null</code>
+ */
+ public static <T> List<T> emptyIfNull(List<T> list) {
+ return list == null ? Collections.<T>emptyList() : list;
+ }
+
/**
* Returns a new list containing all elements that are contained in
* both given lists.
Modified:
commons/proper/collections/trunk/src/main/java/org/apache/commons/collections/MapUtils.java
URL:
http://svn.apache.org/viewvc/commons/proper/collections/trunk/src/main/java/org/apache/commons/collections/MapUtils.java?rev=1421567&r1=1421566&r2=1421567&view=diff
==============================================================================
---
commons/proper/collections/trunk/src/main/java/org/apache/commons/collections/MapUtils.java
(original)
+++
commons/proper/collections/trunk/src/main/java/org/apache/commons/collections/MapUtils.java
Thu Dec 13 21:52:42 2012
@@ -85,7 +85,8 @@ public class MapUtils {
* An empty unmodifiable sorted map.
* This is not provided in the JDK.
*/
- public static final SortedMap<Object, Object> EMPTY_SORTED_MAP =
UnmodifiableSortedMap.unmodifiableSortedMap(new TreeMap<Object, Object>());
+ public static final SortedMap<Object, Object> EMPTY_SORTED_MAP =
+ UnmodifiableSortedMap.unmodifiableSortedMap(new TreeMap<Object,
Object>());
/**
* String used to indent the verbose and debug Map prints.
@@ -1161,6 +1162,20 @@ public class MapUtils {
}
//-----------------------------------------------------------------------
+
+ /**
+ * Returns an immutable empty map if the argument is <code>null</code>,
+ * or the argument itself otherwise.
+ *
+ * @param <K> the key type
+ * @param <V> the value type
+ * @param map the map, possibly <code>null</code>
+ * @return an empty map if the argument is <code>null</code>
+ */
+ public static <K,V> Map<K,V> emptyIfNull(Map<K,V> map) {
+ return map == null ? Collections.<K,V>emptyMap() : map;
+ }
+
/**
* Null-safe check if the specified map is empty.
* <p>
Modified:
commons/proper/collections/trunk/src/main/java/org/apache/commons/collections/SetUtils.java
URL:
http://svn.apache.org/viewvc/commons/proper/collections/trunk/src/main/java/org/apache/commons/collections/SetUtils.java?rev=1421567&r1=1421566&r2=1421567&view=diff
==============================================================================
---
commons/proper/collections/trunk/src/main/java/org/apache/commons/collections/SetUtils.java
(original)
+++
commons/proper/collections/trunk/src/main/java/org/apache/commons/collections/SetUtils.java
Thu Dec 13 21:52:42 2012
@@ -81,6 +81,19 @@ public class SetUtils {
}
//-----------------------------------------------------------------------
+
+ /**
+ * Returns an immutable empty set if the argument is <code>null</code>,
+ * or the argument itself otherwise.
+ *
+ * @param <T> the element type
+ * @param set the set, possibly <code>null</code>
+ * @return an empty set if the argument is <code>null</code>
+ */
+ public static <T> Set<T> emptyIfNull(Set<T> set) {
+ return set == null ? Collections.<T>emptySet() : set;
+ }
+
/**
* Tests two sets for equality as per the <code>equals()</code> contract
* in {@link java.util.Set#equals(java.lang.Object)}.
Modified:
commons/proper/collections/trunk/src/test/java/org/apache/commons/collections/CollectionUtilsTest.java
URL:
http://svn.apache.org/viewvc/commons/proper/collections/trunk/src/test/java/org/apache/commons/collections/CollectionUtilsTest.java?rev=1421567&r1=1421566&r2=1421567&view=diff
==============================================================================
---
commons/proper/collections/trunk/src/test/java/org/apache/commons/collections/CollectionUtilsTest.java
(original)
+++
commons/proper/collections/trunk/src/test/java/org/apache/commons/collections/CollectionUtilsTest.java
Thu Dec 13 21:52:42 2012
@@ -1341,6 +1341,13 @@ public class CollectionUtilsTest extends
assertEquals(CollectionUtils.EMPTY_COLLECTION, coll);
}
+ @Test
+ public void emptyIfNull() {
+ assertTrue(CollectionUtils.emptyIfNull(null).isEmpty());
+ Collection<Object> collection = new ArrayList<Object>();
+ assertSame(collection, CollectionUtils.emptyIfNull(collection));
+ }
+
/**
* This test ensures that {@link Iterable}s are supported by {@link
CollectionUtils}.
* Specifically, it uses mocks to ensure that if the passed in
Modified:
commons/proper/collections/trunk/src/test/java/org/apache/commons/collections/ListUtilsTest.java
URL:
http://svn.apache.org/viewvc/commons/proper/collections/trunk/src/test/java/org/apache/commons/collections/ListUtilsTest.java?rev=1421567&r1=1421566&r2=1421567&view=diff
==============================================================================
---
commons/proper/collections/trunk/src/test/java/org/apache/commons/collections/ListUtilsTest.java
(original)
+++
commons/proper/collections/trunk/src/test/java/org/apache/commons/collections/ListUtilsTest.java
Thu Dec 13 21:52:42 2012
@@ -165,6 +165,13 @@ public class ListUtilsTest extends BulkT
assertEquals(6, list.size());
}
+ public void testEmptyIfNull() {
+ assertTrue(ListUtils.emptyIfNull(null).isEmpty());
+
+ List<Long> list = new ArrayList<Long>();
+ assertSame(list, ListUtils.emptyIfNull(list));
+ }
+
public void testEquals() {
Collection<String> data = Arrays.asList( new String[] { "a", "b", "c"
});
Modified:
commons/proper/collections/trunk/src/test/java/org/apache/commons/collections/MapUtilsTest.java
URL:
http://svn.apache.org/viewvc/commons/proper/collections/trunk/src/test/java/org/apache/commons/collections/MapUtilsTest.java?rev=1421567&r1=1421566&r2=1421567&view=diff
==============================================================================
---
commons/proper/collections/trunk/src/test/java/org/apache/commons/collections/MapUtilsTest.java
(original)
+++
commons/proper/collections/trunk/src/test/java/org/apache/commons/collections/MapUtilsTest.java
Thu Dec 13 21:52:42 2012
@@ -711,6 +711,14 @@ public class MapUtilsTest extends BulkTe
}
//-----------------------------------------------------------------------
+
+ public void testEmptyIfNull() {
+ assertTrue(MapUtils.emptyIfNull(null).isEmpty());
+
+ Map<Long, Long> map = new HashMap<Long, Long>();
+ assertSame(map, MapUtils.emptyIfNull(map));
+ }
+
public void testIsEmptyWithEmptyMap() {
Map<Object, Object> map = new HashMap<Object, Object>();
assertEquals(true, MapUtils.isEmpty(map));
Modified:
commons/proper/collections/trunk/src/test/java/org/apache/commons/collections/SetUtilsTest.java
URL:
http://svn.apache.org/viewvc/commons/proper/collections/trunk/src/test/java/org/apache/commons/collections/SetUtilsTest.java?rev=1421567&r1=1421566&r2=1421567&view=diff
==============================================================================
---
commons/proper/collections/trunk/src/test/java/org/apache/commons/collections/SetUtilsTest.java
(original)
+++
commons/proper/collections/trunk/src/test/java/org/apache/commons/collections/SetUtilsTest.java
Thu Dec 13 21:52:42 2012
@@ -69,6 +69,13 @@ public class SetUtilsTest extends BulkTe
}
}
+ public void testEmptyIfNull() {
+ assertTrue(SetUtils.emptyIfNull(null).isEmpty());
+
+ Set<Long> set = new HashSet<Long>();
+ assertSame(set, SetUtils.emptyIfNull(set));
+ }
+
public void testEquals() {
Collection<String> data = Arrays.asList( new String[] { "a", "b", "c"
});
