线程间通信，wait、notify的使用

PrintChar.java

package com.java.test.thread;

import java.util.concurrent.atomic.AtomicInteger;

/**
 * Created by John on 18/3/19.
 * 使用三个线程使得ABC 循环输出十次
 */
public class PrintABC {

    private static volatile String NEXT_TEXT = "C";
    private static AtomicInteger COUNT = new AtomicInteger(0);

    private static final Object lock = new Object();

    public static void main(String[] args) {
        new Thread(new PrintTask("A")).start();
        new Thread(new PrintTask("B")).start();
        new Thread(new PrintTask("C")).start();
    }

    private static String getNextText() {
        if ("A".equals(NEXT_TEXT)) {
            return "B";
        }

        if ("B".equals(NEXT_TEXT)) {
            return "C";
        }

        if ("C".equals(NEXT_TEXT)) {
            return "A";
        }
        return null;
    }

    private static class PrintTask implements Runnable {

        private String text;

        private PrintTask(String text) {
            this.text = text;
        }

        @Override
        public void run() {
            print();
        }

        private void print() {
            synchronized (lock) {
                for (; COUNT.get() < 10; ) {
                    String nextText = getNextText();
                    if (text.equals(nextText)) {
                        if (text.equals("A")) {
                            System.out.print(COUNT.get() + ":");
                        }
                        System.out.print(text);

                        if (text.equals("C")) {
                            System.out.print("\n");
                            COUNT.incrementAndGet();
                        }
                        NEXT_TEXT = text;
                        lock.notifyAll();
                    }
                    if (COUNT.get() >= 10) {
                        return;
                    }
                    try {
                        lock.wait(10);
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }
            }
        }
    }

}