public class ThreadTester {
public static void main(String[] args) {
SynchronizedQueue queue = new SynchronizedQueue(10);
final int GREETING_COUNT = 100;
Runnable run1 = new Producer("Hello, World!", queue, GREETING_COUNT);
Runnable run2 = new Producer("Goodbye, World!", queue, GREETING_COUNT);
Runnable run3 = new Consumer(queue, 2 * GREETING_COUNT);
Thread thread1 = new Thread(run1);
Thread thread2 = new Thread(run2);
Thread thread3 = new Thread(run3);
thread1.start();
thread2.start();
thread3.start();
}
}
class Producer implements Runnable {
private String greeting;
private SynchronizedQueue queue;
private int greetingCount;
public Producer(String aGreeting, SynchronizedQueue aQueue, int count) {
greeting = aGreeting;
queue = aQueue;
greetingCount = count;
}
public void run() {
try {
int i = 1;
while (i <= greetingCount) {
queue.add(i + ": " + greeting);
i++;
Thread.sleep(2000);
}
} catch (InterruptedException exception) {
}
}
}
class Consumer implements Runnable {
private SynchronizedQueue queue;
private int greetingCount;
public Consumer(SynchronizedQueue aQueue, int count) {
queue = aQueue;
greetingCount = count;
}
public void run() {
try {
int i = 1;
while (i <= greetingCount) {
String greeting = queue.remove();
System.out.println(greeting);
i++;
Thread.sleep(3000);
}
} catch (InterruptedException exception) {
}
}
}
class SynchronizedQueue {
private Object[] elements;
private int head;
private int tail;
private int size;
public SynchronizedQueue(int capacity) {
elements = new Object[capacity];
head = 0;
tail = 0;
size = 0;
}
public synchronized V remove() throws InterruptedException {
while (size == 0)
wait();
V r = (V) elements[head];
head++;
size--;
if (head == elements.length)
head = 0;
notifyAll();
return r;
}
public synchronized void add(V newValue) throws InterruptedException {
while (size == elements.length)
wait();
elements[tail] = newValue;
tail++;
size++;
if (tail == elements.length)
tail = 0;
notifyAll();
}
}