Java Update Jar command not working (using Runtime.getRuntime().exec())

Question

So I am making this builder that is supposed to simply make a config.java file, put the config info it. Compile it. then update an existing jar with it. I have everything working and I am getting no errors, however when I do Runtime.getRuntime().exec("jar uf "+out+" "+ cClass); it seems to fail. I have tried getting the output of said command but it is showing nothing. I also tried to do this manually and it worked fine. So my question is, what is going wrong and how do I fix it?

Runtime.getRuntime().exec("javac "+config);         
File cClass = new File (config.getParentFile().getAbsolutePath() +"/configs.class");
Runtime.getRuntime().exec("jar uf "+out+" "+ cClass);   

Out is the Jar file to be updated, config is the config.java cClass is the config.class

Here is My entire UpdateJar class

import java.io.BufferedReader;
import java.io.File;
import java.io.IOException;
import java.io.InputStreamReader;

public class cmd extends Thread{
private File out;
private File config;
public cmd(File out, File config){
    this.out = out;
    this.config = config;
    this.start();
}
    public void run(){
        try {
            Thread.sleep(5000);
        } catch (InterruptedException e1) {
            e1.printStackTrace();
        }
    try {
        Process p = Runtime.getRuntime().exec("jar uvf "+out+" "+config.getParentFile().getAbsolutePath()+("/configs.class"));
        BufferedReader stdInput = new BufferedReader(new 
                 InputStreamReader(p.getInputStream()));
            BufferedReader stdError = new BufferedReader(new 
                 InputStreamReader(p.getErrorStream()));
            System.out.println(stdInput.readLine());
            System.out.println(stdError.readLine());
    } catch (IOException e) {
        e.printStackTrace();
    }
    }
}

The output it returns is such:

2013-03-28 20:18:58.363 null
2013-03-28 20:18:58.363 [parsing started RegularFileObject[/Users/jorisbolsens/Desktop/configs.java]]
2013-03-28 20:19:04.364 adding: Users/jorisbolsens/Desktop/configs.class(in = 767) (out= 512)(deflated 33%)
2013-03-28 20:19:04.364 null

Out of curiosity I extracted all the files of my out.jar and found that the configs.class is in fact being put into the jar, it is simply being put into a folder. into users.jorisbolsens.Desktop to be specific.

Answer 1

I fixed this, It was so simple that I feel really stupid for not trying this at first. I changed the

Runtime.getRuntime().exec("jar uvf "+out+" "+config.getParentFile().getAbsolutePath()+("/configs.class"));

part to

Runtime.getRuntime().exec("jar uvf "+out+" -C "+config.getParentFile().getAbsolutePath()+ " configs.class");

and everything works perfectly now. I would like to thank ericson for all his help.