Execute .jar file from a Java program

I suggest you use a ProcessBuilder and start a new JVM.

Here is something to get you started:

ProcessBuilder pb = new ProcessBuilder("/path/to/java", "-jar", "your.jar");
pb.directory(new File("preferred/working/directory"));
Process p = pb.start();

    Process proc = Runtime.getRuntime().exec("java -jar Validate.jar");
    proc.waitFor();
    // Then retreive the process output
    InputStream in = proc.getInputStream();
    InputStream err = proc.getErrorStream();

    byte b[]=new byte[in.available()];
    in.read(b,0,b.length);
    System.out.println(new String(b));

    byte c[]=new byte[err.available()];
    err.read(c,0,c.length);
    System.out.println(new String(c));