Odpalanie minecraft.jar w javie

package piotrek54pl.gmail.com;

import java.applet.Applet;
import java.io.File;
import java.net.URISyntaxException;
import java.util.ArrayList;

public class Launcher
{
    private static ProcessBuilder p = new ProcessBuilder();
    private static Process process;

    public static String username = "Drewno";
    public static String sessionid = "12345";

    public static void start() throws Exception
    {
            String pathToJar = Launcher.class.getProtectionDomain().getCodeSource().getLocation().toURI().getPath();

            ArrayList params = new ArrayList();
            params.add("javaw");
            params.add("-Xms512m");
            params.add("-Xmx1024m");
            params.add("-Djava.library.path=\\bin\\natives");
            params.add("-classpath");
            params.add("bin\\minecraft.jar;bin\\jinput.jar;bin\\lwjgl.jar;bin\\lwjgl_util.jar");
            params.add("-Djava.library.path=\"bin\\natives\"");
            params.add("net.minecraft.client.Minecraft");
            params.add(username);
            params.add(sessionid);

            File workdir = new File(System.getenv("APPDATA")+"\\.minecraft\\");
            p.command(params);
            p.directory(workdir);
            process = p.start();
            if(process == null)
            {
                System.out.println("ERR");
                System.exit(0);
            }
    }

}