交替输出A1B2C3D4...-优快云博客

本文链接：https://blog.youkuaiyun.com/sdmanooo/article/details/114022992

这篇博客展示了如何在Java中使用LockSupport、Semaphore、ReentrantLock和BlockingQueue等并发控制工具，来实现两个线程交替输出字母和数字序列（如A1B2C3...）。每个示例都确保了线程间的同步和正确顺序的输出。

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定义两个线程，一个输出ABCD，一个输出1234，但是要求最终结果交替输出A1B2C3D4....

这貌似是个面试题，尝试写了下，方法应该很多。介绍几种写法：

/**
 * 使用LockSupport交替输出A1B2C3....
 */
public class ByteNumber {

    static Thread t1 = null;
    static Thread t2 = null;

    public static void main(String[] args) throws InterruptedException {
        t1 = new Thread(new Runnable() {
            public void run() {
                for(char i=65;i<91;i++){
                    System.out.println(i);
                    LockSupport.unpark(t2);
                    LockSupport.park();
                }
            }
        });
        t2 = new Thread(new Runnable() {
            public void run() {
                for(int i=1;i<27;i++){
                    LockSupport.park();
                    System.out.println(i);
                    LockSupport.unpark(t1);

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

/**
 * 使用Semaphore信号量交替输出A1B2C3....
 */
public class ByteNumber2 {

    public static void main(String[] args) throws InterruptedException {
        final Semaphore semaphore1 = new Semaphore(0);
        final Semaphore semaphore2 = new Semaphore(0);

        Thread t1 = new Thread(new Runnable() {
            public void run() {
                for(char i=65;i<91;i++){
                    try {
                        semaphore1.acquire();
                        System.out.println(i);
                        semaphore2.release();
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }
            }
        });
        Thread t2 = new Thread(new Runnable() {
            public void run() {
                for(int i=1;i<27;i++){
                    try {
                        semaphore1.release();
                        semaphore2.acquire();
                        System.out.println(i);
                    } catch (Exception e) {
                        e.printStackTrace();
                    }
                }
            }
        });
        t1.start();
        t2.start();
    }
}


/**
 * 使用ReentrantLock信号量交替输出A1B2C3....
 */
public class ByteNumber3 {
    public static void main(String[] args) throws InterruptedException {
        final  ReentrantLock lock = new ReentrantLock(true);
        final Condition byteCon = lock.newCondition();
        final Condition numCon = lock.newCondition();

        Thread t1 = new Thread(new Runnable() {
            public void run() {
                try {
                    lock.lock();
                     for(char i=65;i<91;i++){
                        System.out.println(i);
                        numCon.signal();
                        byteCon.await();
                    }
                    numCon.signal();
                }catch (Exception e) {
                    e.printStackTrace();
                } finally {
                    lock.unlock();
                }

            }
        });
        Thread t2 = new Thread(new Runnable() {
            public void run() {
                try {
                    lock.lock();
                    for(int i=1;i<27;i++){
                        System.out.println(i);
                        byteCon.signal();
                        numCon.await();
                    }
                    byteCon.signal();
                } catch (Exception e) {
                    e.printStackTrace();
                } finally {
                    lock.unlock();
                }
            }
        });
        t1.start();
        Thread.sleep(0);
        t2.start();
    }
}


/**
 * 使用BlockingQueue信号量交替输出A1B2C3....
 */
public class ByteNumber6 {

    public static void main(String[] args) throws InterruptedException {
        final BlockingQueue<String> b1 = new LinkedBlockingQueue<>(1);
        final BlockingQueue<String> b2 = new LinkedBlockingQueue<>(1);

        Thread t1 = new Thread(new Runnable() {
            public void run() {
                for(char i=65;i<91;i++){
                    try {
                        b2.take();
                        System.out.println(i);
                        b1.put("ok");
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }
            }
        });
        Thread t2 = new Thread(new Runnable() {
            public void run() {
                for(int i=1;i<27;i++){
                    try {
                        b2.put("ok");
                        b1.take();
                        System.out.println(i);
                    } catch (Exception e) {
                        e.printStackTrace();
                    }
                }
            }
        });
        t1.start();
        t2.start();
    }
}