Executing a jar in a Java program

[laila NiHai]

Hello,

I just started to learn how to use the ProcessBuilder to invoke another java program (jar). I have added this jar to the "lib" of the calling java program, but when executed I keep getting the error:

Exception in thread "main" java.lang.NoClassDeffoundError:...
Caused by: java.lang.ClassNotFoundException:...

I understand what this error means, but what I don't understand is running the same command directly in the shell works fine, but running it in the java program then i got the mentioned error. Not sure what I did wrong in using the ProcessBuilder (built upon example from the article recommended thisThread

Here is the code:

import java.util.*;
import java.io.*;
class StreamGobbler extends Thread
{
    InputStream is;
    String type;
    
    StreamGobbler(InputStream is, String type)
    {
        this.is = is;
        this.type = type;
    }
    
    public void run()
    {
        try
        {
            InputStreamReader isr = new InputStreamReader(is);
            BufferedReader br = new BufferedReader(isr);
            String line=null;
            while ( (line = br.readLine()) != null)
                System.out.println(type + ">" + line);    
            } catch (IOException ioe)
              {
                ioe.printStackTrace();  
              }
    }
}
public class GoodWindowsExec
{
    public static void main(String args[])
    {
        if (args.length < 1)
        {
            System.out.println("USAGE: java GoodWindowsExec <cmd>");
            System.exit(1);
        }
        
        try
        {   
            String command = "java";
	    String options = "-jar test.jar";

            ProcessBuilder pB = new ProcessBuilder(command, options);

            Process p = processBuilder.start();

            // any error message?
            StreamGobbler errorGobbler = new 
                StreamGobbler(proc.getErrorStream(), "ERROR");            
            
            // any output?
            StreamGobbler outputGobbler = new 
                StreamGobbler(proc.getInputStream(), "OUTPUT");
                
            // kick them off
            errorGobbler.start();
            outputGobbler.start();
                                    
            // any error???
            int exitVal = proc.waitFor();
            System.out.println("ExitValue: " + exitVal);        
        } catch (Throwable t)
          {
            t.printStackTrace();
          }
    }
}

[laila NiHai]

Could someone please give me pointers? I've Googled for days...and still haven't found a good example and/or explaination. Any advice would be greatly appreciated!

[Ove Lindström]

On what line do you get the ClassNotFound?

I also think that ProcessBuilder starts from the working directory where the parent process is executed. If so, then the command line should be "java -jar lib/test.jar" if the test.jar is in the lib-directory.

Edit: Yep, I was right. See http://download.oracle.com/javase/7/docs/api/java/lang/ProcessBuilder.html#directory%28%29 on how to find out the current working directory.

[laila NiHai]

Hi Ove, thank you for your reply....

I get the error at the line:

Process p = processBuilder.start();   

It looks like the jar file is found and it tries to load the main class... The "test.jar" also has it's own /lib folder... which I tried to also copy it to the main program /lib folder, but still didn't help.