生产者消费者问题java

生产者消费者问题是一个经典的多线程同步问题，在Java中可以使用synchronized关键字和wait()/notify()方法来实现。

以下是一个简单的Java代码示例，实现了一个生产者消费者模型：

class Buffer {
    private int contents;
    private boolean available = false;

    public synchronized int get() {
        while (available == false) {
            try {
                wait();
            } catch (InterruptedException e) {
            }
        }
        available = false;
        notifyAll();
        return contents;
    }

    public synchronized void put(int value) {
        while (available == true) {
            try {
                wait();
            } catch (InterruptedException e) {
            }
        }
        contents = value;
        available = true;
        notifyAll();
    }
}

class Producer extends Thread {
    private Buffer buffer;

    public Producer(Buffer buffer) {
        this.buffer = buffer;
    }

    public void run() {
        for (int i = 0; i < 10; i++) {
            buffer.put(i);
            System.out.println("Producer put: " + i);
            try {
                sleep((int)(Math.random() * 100));
            } catch (InterruptedException e) {
            }
        }
    }
}

class Consumer extends Thread {
    private Buffer buffer;

    public Consumer(Buffer buffer) {
        this.buffer = buffer;
    }

    public void run() {
        int value;
        for (int i = 0; i < 10; i++) {
            value = buffer.get();
            System.out.println("Consumer get: " + value);
            try {
                sleep((int)(Math.random() * 100));
            } catch (InterruptedException e) {
            }
        }
    }
}

public class ProducerConsumerTest {
    public static void main(String[] args) {
        Buffer buffer = new Buffer();
        Producer producer = new Producer(buffer);
        Consumer consumer = new Consumer(buffer);
        producer.start();
        consumer.start();
    }
}

在上面的代码中，Buffer类表示缓冲区，Producer类和Consumer类分别表示生产者和消费者。通过wait()和notifyAll()方法来实现线程之间的同步。当缓冲区为空时，消费者线程调用wait()方法进入等待状态，直到生产者线程往缓冲区放入数据并调用notifyAll()方法唤醒消费者线程。当缓冲区已满时，生产者线程调用wait()方法进入等待状态，直到消费者线程从缓冲区取出数据并调用notifyAll()方法唤醒生产者线程。