public class Sibling extends Thread {

    // Constructor for Sibling
Sibling(String name, int priority) {
    super(name);
    setPriority(priority);
  }

public void run() {
    int count = 1000000;
    try {
        sleep(200);
    } catch (InterruptedException e) {};
    // Countdown, with reports every 100,000 iterations
    while (count-- > 0) {
        if (count%100000 == 0)
        System.out.println(getName() + ": " + count);
    }
  }

private static void usage() {
    System.err.println("Usage: java Sibling p1 p2" +
        "where p1 and p2 are greater than 0\n and" +
        "less than or equal to 10");
    System.exit(1);
    }

private static int checkArg(String arg) {
    int i = 0;
    try {
       i = Integer.parseInt(arg);
    } catch (NumberFormatException e) { usage();}
    if ( i < 1 || i > 10 ) usage();
    return i;
  }


public static void main(String args[]) {
    if (args.length != 2) usage();
    int p1 = checkArg(args[0]);
    int p2 = checkArg(args[1]);
    // Args are okay, let's get grandparent ThreadGroup
    ThreadGroup next = Thread.currentThread().getThreadGroup();
    ThreadGroup top = next;
    while (next != null) {
        top = next;
        next = next.getParent();
    }
    // Now, create and start two Siblings
    Sibling sib1 = new Sibling("Older", p1);
    Sibling sib2 = new Sibling("Younger", p2); 
    sib1.start();
    sib2.start();
    // List all ThreadGroups and Threads
    top.list();
    // Wait for lower priority Sibling to complete
    Sibling lower = (p1>p2)?sib2:sib1;
    try { lower.join(); } 
    catch (InterruptedException e) {};
    System.out.println("Main Thread exiting.");
    }
}