public class ReadAndWriteLock {
    public static void main(String[] args) {
        final QueueJ q = new QueueJ();
        for (int i = 0; i <3 ; i++) {
            new Thread(){
                @Override
                public void run() {
                    while (true) {
                        q.get();
                    }
                }
            }.start();

            new Thread(){
                @Override
                public void run() {
                    q.put(new Random().nextInt(1000));
                }
            }.start();
        }
    }
}
class QueueJ {
    private Object data = null;//共享数据，只能有一个线程
    private ReentrantReadWriteLock rwl = new ReentrantReadWriteLock();
    public void get() {
        rwl.readLock().lock();
        try {
            System.out.println(Thread.currentThread().getName() + "will read");
            Thread.sleep((long)(Math.random()*1000));
            System.out.println(Thread.currentThread().getName() + "have read");
        }catch (InterruptedException e) {
            e.printStackTrace();
        }finally {
            rwl.readLock().unlock();
        }
    }
    public void put(Object data) {
        rwl.writeLock().lock();
        try {
            System.out.println(Thread.currentThread().getName() + "will write");
            Thread.sleep((long)(Math.random()*1000));
            this.data = data;
            System.out.println(Thread.currentThread().getName() + "have write");
        }catch (InterruptedException e){
            e.printStackTrace();
        }finally {
            rwl.writeLock().unlock();
        }
    }
}

读之前，加上读锁，写之前加上写锁