题目：多线程交替打印1A2B3C……26Z

  1. 定义统一变量
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private static ExecutorService executorService = Executors.newSingleThreadExecutor();
private static ReentrantLock reentrantLock = new ReentrantLock();
private static volatile AtomicInteger ReadyToRun = new AtomicInteger(0);
private static volatile int data = 1;
private static Object object = new Object();
private static volatile boolean flag = true;
  1. 方法一
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public static void printABC3() {
        new Thread(new Runnable() {
            @Override
            public void run() {
                while (true) {
                    if (data > 26) {
                        ReadyToRun.set(1);
                        System.out.println(Thread.currentThread().getName() + ": stop");
                        break;
                    }
                    while (ReadyToRun.get() == 0) {
                        if (data > 26){
                            ReadyToRun.set(1);
                            break;
                        }
                        System.out.println(Thread.currentThread().getName() + ":  "+  data);
                        ReadyToRun.set(1);
                    }

                }
            }
        },"t1").start();

        new Thread(new Runnable() {
            @Override
            public void run() {
                while (true) {
                    if (data >= 27){
                        break;
                    }
                    while (ReadyToRun.get() == 1) {
                        System.out.println(Thread.currentThread().getName()  + " : " + (char) (data + 64));
                        data++;
                        if (data > 26) {
                            System.out.println(Thread.currentThread().getName() + ": stop");
                            break;
                        }
                        ReadyToRun.set(0);
                    }
                }
            }
        },"t2").start();

    }

3.方法二：

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/**
    * wait方法是object中的方法。调用wait方法之后，会立即释放锁，该线程放到等待池中，到有notify()或者notifyAll()调用的时候，会将该线程
    * 从等待池放到锁池中，锁池的中线程竞争该锁。notify()方法不会释放锁,必须等待notfiy()所在的synchronized块执行结束才会结束
    */
   public static void printABC2() {
       new Thread(new Runnable() {
           @Override
           public void run() {
               while (true) {
                   synchronized (object) {
                       if (data > 26) {
                           System.out.println(Thread.currentThread().getName() + " stop" );
                           // 这里加入object.notify()让线程2正常退出
                           object.notify();
                           break;
                       }

                       if (flag) {
                           System.out.print(data);
                           flag = false;
                           try {
                               object.notify();
                               object.wait();
                           } catch (InterruptedException e) {
                               e.printStackTrace();
                           }
                       }
                   }
               }
           }
       },"t1").start();

       new Thread(new Runnable() {
           @Override
           public void run() {
               while (true) {
                   if (data > 26) {
                       System.out.println(Thread.currentThread().getName() + " stop" );
                       break;
                   }
                   synchronized (object) {
                       if (!flag) {
                           System.out.print((char) (data + 64));
                           data++;
                           flag = true;
                           try {
                               object.notify();
                               object.wait();
                           } catch (InterruptedException e) {
                               e.printStackTrace();
                           }
                       }
                   }
               }
           }
       },"t2").start();
   }

3:

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public static void printABC1() {
        new Thread(new Runnable() {
            @Override
            public void run() {
                while (true) {
                    reentrantLock.lock();
                    if (data > 26) {
                        reentrantLock.unlock();
                        break;
                    }
                    if (flag) {
                        System.out.print(data);
                        flag = false;
                    }
                    reentrantLock.unlock();
                }
            }
        }, "thread-num").start();

        new Thread(new Runnable() {
            @Override
            public void run() {
                while (true) {
                    reentrantLock.lock();
                    if (data > 26) {
                        // 注意解锁
                        reentrantLock.unlock();
                        break;
                    }
                    if (!flag) {
                        System.out.print((char) (data + 64));
                        flag = true;
                        data++;
                    }
                    reentrantLock.unlock();
                }
            }
        }, "thread-char").start();
    }
  1. newSingleThreadExecutor方法是保证提交的任务顺序执行
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public static void printABC() {
        int[] data = new int[26];
        for (int i = 0; i < 26; i++) {
            data[i] = i + 1;
        }

        for (int i = 0; i < 26; i++) {
            int temp = data[i];
            executorService.submit(new Runnable() {
                @Override
                public void run() {
                    System.out.print(temp + "" + (char) (temp + 64));
                }
            });
        }
    }

本文地址： http://byejd.github.io/2019/11/20/%E4%B8%A4%E4%B8%AA%E7%BA%BF%E7%A8%8B%E4%BA%A4%E6%9B%BF%E6%89%93%E5%8D%B0%E5%AD%97%E7%AC%A6/