Java并发编程学习

1.4 wait() 与 notify

例如消息队列生成和消费消息时候，可以用  wait (),  notify 通知对方

wait 和 notify 必须在 synchronized方法里。

1)  wait

释放当前线程的锁，线程进入等待状态，直到其他线程调用该对象的notify

2) notify

其他随机一个线程对应的等待状态解除。可以竞争当前锁。如果要解除所有解除线程的等待状态使用 notifyAll

package concurrent;

public class MyQueue {
    private String[] data = new String[10];
    private int size = 0;
    private int getInd = 0;
    private int putInd = 0;

    public synchronized void put(String ele) throws InterruptedException {
        if (size == 10) {
            wait();
            put(ele);
        } else {
            size++;
            data[putInd++] = ele;
            if (putInd == data.length) putInd = 0;
            System.out.println("produce " + ele);
            notify();
        }
    }

    public synchronized void get() throws InterruptedException {
        if (size == 0) {
            wait();
            get();
        } else {
            size--;
            String consume = data[getInd++];
            if (getInd == data.length) getInd = 0;
            System.out.println("consume " + consume);
            notify();
        }
    }
}

package concurrent;

public class ConsumerThread extends Thread{
    private final MyQueue myQueue;

    public ConsumerThread(MyQueue myQueue) {
        this.myQueue = myQueue;
    }

    @Override
    public void run() {
        while (true) {
            try {
                myQueue.get();
            } catch (InterruptedException e) {
                throw new RuntimeException(e);
            }
        }
    }
}

package concurrent;

public class ProducerThread extends Thread {
    private final MyQueue myQueue;
    private int index = 1;

    public ProducerThread(MyQueue myQueue) {
        this.myQueue = myQueue;
    }

    @Override
    public void run() {
        while (true) {
            try {
                if (index == 10) index = 1;
                String putStr = "data" + index;
                myQueue.put(putStr);
                index++;
            } catch (InterruptedException e) {
                throw new RuntimeException(e);
            }
        }
    }

}

package concurrent;

public class Main {
    public static void main(String[] args) {
        MyQueue myQueue = new MyQueue();
        new ConsumerThread(myQueue).start();
        new ProducerThread(myQueue).start();
    }
}

1.5