It means Class is not in your classpath.
-----Original Message-----
From: praveenesh kumar [mailto:[email protected]]
Sent: Tuesday, May 24, 2011 3:31 PM
To: [email protected]
Subject: How to compile simple Hbase code ?
I am simply using HBase API, not doing any Map-reduce work on it.
Following is the code I have written , simply creating the file on HBase:
import java.io.IOException;
import org.apache.hadoop.hbase.HBaseConfiguration;
import org.apache.hadoop.hbase.HColumnDescriptor;
import org.apache.hadoop.hbase.HTableDescriptor;
import org.apache.hadoop.hbase.client.Get;
import org.apache.hadoop.hbase.client.HBaseAdmin;
import org.apache.hadoop.hbase.client.HTable;
import org.apache.hadoop.hbase.client.Put;
import org.apache.hadoop.hbase.client.Result;
import org.apache.hadoop.hbase.client.ResultScanner;
import org.apache.hadoop.hbase.client.Scan;
import org.apache.hadoop.hbase.util.Bytes;
public class ExampleClient {
public static void main(String args []) throws IOException {
HBaseConfiguration config = new HBaseConfiguration();
HBaseAdmin admin = new HBaseAdmin(config);
HTableDescriptor htd = new HTableDescriptor("test");
HColumnDescriptor hcd = new HColumnDescriptor("data");
htd.addFamily(hcd);
admin.createTable(htd);
byte [] tablename = htd.getName();
HTableDescriptor [] tables = admin.listTables();
if(tables.length !=1 && Bytes.equals(tablename, tables[0].getName()))
{
throw new IOException("Failed to create table");
}
HTable table = new HTable(config,tablename);
byte[] row1 = Bytes.toBytes("row1");
Put p1 = new Put(row1);
byte[] databytes = Bytes.toBytes("data");
p1.add(databytes,Bytes.toBytes("1"),Bytes.toBytes("value1"));
table.put(p1);
Get g = new Get(row1);
Result result = table.get(g);
System.out.println("Get : "+ result);
Scan scan = new Scan();
ResultScanner scanner = table.getScanner(scan);
try
{
for(Result scannerResult: scanner)
{
System.out.println("Scan : " + scannerResult);
}
}catch(Exception e ){
e.printStackTrace();
}
finally{
scanner.close();
}
table.close();
}
}
Now I have set the classpath variable in /etc/environment as
*
MYCLASSPATH="/usr/local/hadoop/hadoop/hadoop-0.20.2-core.jar:/usr/local/hadoop/hbase/hbase/hbase-0.20.6.jar:/usr/local/hadoop/hbase/hbase/lib/zookeeper-3.2.2.jar
*
now I am compiling my code with javac command
*$javac -classpath $MYCLASSPATH ExampleClient.java
*
It is working fine.
While running, I am using java command
*$java -classpath $MYCLASSPATH ExampleClient*,
then I am getting the following error :
*Exception in thread "main" java.lang.NoClassDefFoundError: ExampleClient
Caused by: java.lang.ClassNotFoundException: ExampleClient*
* at java.net.URLClassLoader$1.run(URLClassLoader.java:217)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:205)
at java.lang.ClassLoader.loadClass(ClassLoader.java:321)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:294)
at java.lang.ClassLoader.loadClass(ClassLoader.java:266)*
Could not find the main class: ExampleClient. Program will exit.
But I am running the code from the same location. and ExampleClient.class file
exists at that location.
________________________________
Write to us for a Free Gold Pass to the Cloud Computing Expo, NYC to attend a
live session by Head of Impetus Labs on ‘Secrets of Building a Cloud Vendor
Agnostic PetaByte Scale Real-time Secure Web Application on the Cloud ‘.
Looking to leverage the Cloud for your Big Data Strategy ? Attend Impetus
webinar on May 27 by registering at http://www.impetus.com/webinar?eventid=42 .
NOTE: This message may contain information that is confidential, proprietary,
privileged or otherwise protected by law. The message is intended solely for
the named addressee. If received in error, please destroy and notify the
sender. Any use of this email is prohibited when received in error. Impetus
does not represent, warrant and/or guarantee, that the integrity of this
communication has been maintained nor that the communication is free of errors,
virus, interception or interference.
