package inverview.threadjoin;

public class JoinDemo {

private static class ParallelTask implements Runnable {

private Thread predecessor;

@Override

public void run() {

System.out.println(Thread.currentThread().getName() + " Started");

if (predecessor != null) {

try {

predecessor.join();

} catch (InterruptedException e) {

e.printStackTrace();

}

}

System.out.println(Thread.currentThread().getName() + " Finished");

}

public void setPredecessor(Thread t) {

this.predecessor = t;

}

}

public static void main(String[] args) {

// we have three threads and we need to run in the

// order T1, T2 and T3 i.e. T1 should start first

// and T3 should start last.

// You can enforce this ordering using join() method

// but join method must be called from run() method

// because the thread which will execute run() method

// will wait for thread on which join is called.

ParallelTask task1 = new ParallelTask();

ParallelTask task2 = new ParallelTask();

ParallelTask task3 = new ParallelTask();

final Thread t1 = new Thread(task1, "Thread - 1");

final Thread t2 = new Thread(task2, "Thread - 2");

final Thread t3 = new Thread(task3, "Thread - 3");

task2.setPredecessor(t1);

task3.setPredecessor(t2);

// now, let's start all three threads

t3.start();

t2.start();

t1.start();

}

}