Sanjay;
Here's an example of two threads in a producer/consumer relationship. There's this tank, you see, and the consumer wants to empty it. Unfortunately, he can't empty it until the producer fills it, and so the tank makes him wait. Try to tease it apart yourself; if you have any questions I'll try to answer them. (Don't worry right now about the call to <code>sleep</code>, that's just there to make absolutely sure the consumer gets the lock first. If it didn't, my contrived example might deadlock.)
<pre><code>
class SimpleSync {
public static void main( String[] args ) {
Tank theMonitor = new Tank();
Thread dependentThread = new Thread( new Consumer( theMonitor ), "consumer" );
Thread providerThread = new Thread( new Producer( theMonitor ), "producer" );
dependentThread.start();
try {
Thread.currentThread().sleep( 100 );
} catch (InterruptedException e) {}
providerThread.start();
}
}
class Consumer implements Runnable {
private Tank tank;
public Consumer( Tank monitor ) {
tank = monitor;
}
public void run() {
tank.empty();
System.out.println( "Consumer.run() exiting - bye!" );
}
}
class Producer implements Runnable {
private Tank tank;
public Producer( Tank monitor ) {
tank = monitor;
}
public void run() {
tank.fill();
System.out.println( "Producer.run() exiting - bye!" );
}
}
class Tank {
private boolean filled = false;
public synchronized void fill() {
System.out.println( Thread.currentThread().getName() + " got the lock." );
filled = true;
notifyAll();
System.out.println( Thread.currentThread().getName() + " filled the tank." );
}
public synchronized void empty() {
System.out.println( Thread.currentThread().getName() + " got the lock." );
while (!filled) {
try {
System.out.println( Thread.currentThread().getName() + " must wait." );
wait();
} catch (InterruptedException e) {}
}
filled = false;
System.out.println( Thread.currentThread().getName() + " emptied the tank." );
}
}
</code></pre>
