gistfile1.txt

package Thread;

import java.util.Random;
import java.util.concurrent.locks.*;

/**
 * Created by kevinsteppe on 2/10/15.
 */
public class ThreadDemoExc {

    public static final int numLoops = 8;
    private static int num_threads = 4;
    private static Lock lock = new ReentrantLock() ;
    public static void main(String[] args) throws Exception {
        Thread t1 = new Thread(new ThreadDemo(0,lock));
        Thread t2 = new Thread(new ThreadDemo(1,lock));
        t1.start();
        t2.start();
        t1.join();
        t2.join(); //wait for both
        System.out.println("===== end loop =====");
    }
}

class ThreadDemo implements Runnable {

    private static Lock lock ;

    int id;
    Random random = new Random();

    public ThreadDemo(int i,Lock lock) {
        id = i;
        this.lock=lock;
    }

    public void run() {
        try {
            lock.lock();
            for (int i = 0; i < 10; i++) {

                System.out.println("Hello World "+id);
                Thread.yield();
                int x = random.nextInt(4);

                
                if (x == id) {
                    lock.unlock();
                    Thread.sleep(200);
                    lock.lock();
                    throw new Exception("An exception! "+id);
                }
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            lock.unlock();
        }

    }
}

output.txt

run:
Hello World
Hello World
Hello World
Hello World
Hello World
Hello World
Hello World
Hello World
Hello World
===== end loop =====
java.lang.Exception: An exception!
	at Thread.ThreadDemo.run(ThreadDemoExc.java:49)
	at java.lang.Thread.run(Thread.java:724)
Exception in thread "Thread-1" java.lang.Exception: An exception!
	at Thread.ThreadDemo.run(ThreadDemoExc.java:49)
	at java.lang.Thread.run(Thread.java:724)
java.lang.IllegalMonitorStateException
	at java.util.concurrent.locks.ReentrantLock$Sync.tryRelease(ReentrantLock.java:155)
	at java.util.concurrent.locks.AbstractQueuedSynchronizer.release(AbstractQueuedSynchronizer.java:1260)
	at java.util.concurrent.locks.ReentrantLock.unlock(ReentrantLock.java:460)
	at Thread.ThreadDemo.run(ThreadDemoExc.java:55)
	at java.lang.Thread.run(Thread.java:724)
Exception in thread "Thread-0" java.lang.IllegalMonitorStateException
	at java.util.concurrent.locks.ReentrantLock$Sync.tryRelease(ReentrantLock.java:155)
	at java.util.concurrent.locks.AbstractQueuedSynchronizer.release(AbstractQueuedSynchronizer.java:1260)
	at java.util.concurrent.locks.ReentrantLock.unlock(ReentrantLock.java:460)
	at Thread.ThreadDemo.run(ThreadDemoExc.java:55)
	at java.lang.Thread.run(Thread.java:724)