Hadoop 2.6.0 Browsing filesystem Java



I have installed a basic hadoop cluster on CentOS 6.6 and want to write a few basic programs (browse the filesystem, delete/add files, etc) but I’m struggling to get even the most basic app working.

When running some basic code to list the contents of a directory to the console I get the following error:

Exception in thread "main" java.lang.NoSuchMethodError: org.apache.hadoop.ipc.RPC.getProxy(Ljava/lang/Class;JLjava/net/InetSocketAddress;Lorg/apache/hadoop/security/UserGroupInformation;Lorg/apache/hadoop/conf/Configuration;Ljavax/net/SocketFactory;ILorg/apache/hadoop/io/retry/RetryPolicy;Z)Lorg/apache/hadoop/ipc/VersionedProtocol;
    at org.apache.hadoop.hdfs.DFSClient.createRPCNamenode(DFSClient.java:135)
    at org.apache.hadoop.hdfs.DFSClient.<init>(DFSClient.java:280)
    at org.apache.hadoop.hdfs.DFSClient.<init>(DFSClient.java:245)
    at org.apache.hadoop.hdfs.DistributedFileSystem.initialize(DistributedFileSystem.java:100)
    at mapreducetest.MapreduceTest.App.main(App.java:36)

My pom.xml dependencies

          <dependencies>    
            <dependency>                                                                                                                                       
                <groupId>org.apache.hadoop</groupId>                                                                                                           
                <artifactId>hadoop-common</artifactId>                                                                                                         
                <version>2.6.0</version>                                                                                            
            </dependency>  

            <dependency>
              <groupId>org.apache.hadoop</groupId>
              <artifactId>hadoop-core</artifactId>
              <version>1.2.1</version>
            </dependency>       
          </dependencies>

The code:

import java.io.IOException;
import java.net.URI;
import java.net.URISyntaxException;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileStatus;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.hdfs.DistributedFileSystem;

public class App 
{   
    public static void main( String[] args ) throws IOException, URISyntaxException
    {


        Configuration conf = new Configuration();
        FileSystem fs = new DistributedFileSystem();
        fs.initialize(new URI("hdfs://localhost:9000/"), conf);


        for (FileStatus f :fs.listStatus(new Path("/")))
        {
            System.out.println(f.getPath().getName());                  
        }

        fs.close();

    }
}

The error is being thrown after calling fs.initialize(). I’m really not sure what the issue is here. Am I missing dependencies? Are they the wrong version?

Answer

I was running this by calling “java -jar app.jar …. etc” I should have been using “hadoop jar app.jar”.

Worked as intended when I ran it correctly.



Source: stackoverflow