java线程间的通信

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increase断点在number++,线程被唤醒之后会从这里执行；

decrease断点在number--,线程被唤醒之后会从这里执行；

package testSynchronized;

public class Demo4 {
	private int number;

	public synchronized void increase() {
		while (0 != number) {
			try {
				wait();
			} catch (InterruptedException e) {
				e.printStackTrace();
			}
		}

		// 能执行到这里说明已经被唤醒
		// 并且number为0
		number++;
		System.out.println(number);

		// 通知A在等待的线程
		notifyAll();
	}

	public synchronized void decrease() {
		while (0 == number) {
			try {
				wait();
			} catch (InterruptedException e) {
				e.printStackTrace();
			}

		}

		// 能执行到这里说明已经被唤醒
		// 并且number不为0
		number--;
		System.out.println(number);
		notifyAll();
	}

	public static class IncreaseThread extends Thread {
		private Demo4 Demo4;

		public IncreaseThread(Demo4 Demo4) {
			this.Demo4 = Demo4;
		}

		@Override
		public void run() {
			for (int i = 0; i < 20; ++i) {
				// 进行一定的延时
				try {
					Thread.sleep((long) Math.random() * 1000);
				} catch (InterruptedException e) {
					e.printStackTrace();
				}

				// 进行增加操作
				Demo4.increase();
			}
		}

	}

	public static class DecreaseThread extends Thread {
		private Demo4 Demo4;

		public DecreaseThread(Demo4 Demo4) {
			this.Demo4 = Demo4;
		}

		@Override
		public void run() {
			for (int i = 0; i < 20; ++i) {
				// 进行一定的延时
				try {
					Thread.sleep((long) Math.random() * 1000);
				} catch (InterruptedException e) {
					e.printStackTrace();
				}

				// 进行减少操作
				Demo4.decrease();
			}
		}

	}

	public static void main(String[] args) {
		Demo4 Demo4 = new Demo4();

		Thread t1 = new IncreaseThread(Demo4);
		Thread t2 = new DecreaseThread(Demo4);
		
		Thread t3 = new IncreaseThread(Demo4);
		Thread t4 = new DecreaseThread(Demo4);

		t1.start();
		t2.start();
		t3.start();
		t4.start();
	}

}