I would say that the reason you are not seeing anything is to do with your stdout / stderr streams getting redirected (i.e. to the bash shell). If you change your code to something akin to the following.

public class T
{
  public static void main(String args[]) throws Exception
  {
    String[] cmd = {"/bin/bash", "-c", "echo Simon > ./log.log"};
    Runtime.getRuntime().exec(cmd);
  }
}

Then you will see that, assuming that the access rights are correct, a file called 'log.log' has been created conatining the string 'simon'. This implies that the commands are being run correctly. Now try the following.

public class T
{
  public static void main(String args[]) throws Exception
  {
    String[] cmd = {"/bin/bash", "-c", "/bin/ls > ./log.log"};
    Runtime.getRuntime().exec(cmd);
  }
}

Now the file contains the results of your 'ls' operation.

Regards.