Launch Portable Minecraft with Java

// Compile to executable .jar to launch Minecraft Portable with Java
import java.util.Map;

public class Exec {

    public static void main(String[] args) throws Exception
    {
        String path = System.getProperty("user.dir");
        String drive = path.substring(0,1);

        ProcessBuilder pb = new ProcessBuilder("java","-jar", drive + ":/Minecraft Portable/mcp_data/launcher/Minecraft.jar");
        Map<String, String> env = pb.environment();
        env.put("APPDATA", drive + ":/Minecraft Portable/mcp_data/");
        pb.start();
    }

}