run system calls through java

import java.io.*;
public class Hello {

    public static void main(String args[]) {
        try {
            Runtime r = Runtime.getRuntime();
Process p = r.exec("ls -l");
p.waitFor();
BufferedReader b = new BufferedReader(new InputStreamReader(p.getInputStream()));
String line = "";

while ((line = b.readLine()) != null) {
  System.out.println(line);
}
   }     catch(Exception e1) {}
       

        System.out.println("finished.");
    }
}

hadoop help

http://b2ctran.wordpress.com/category/hadoop/
http://www.michael-noll.com/tutorials/running-hadoop-on-ubuntu-linux-single-node-cluster/
http://b2ctran.wordpress.com/2013/08/26/install-hadoop-1-1-2-on-ubuntu-12-04/
http://technsolution.blogspot.in/2013/08/hadoop-installation-on-ubuntu-1204.html