线程间通讯（交替打印ABC）

package com.kaibing.thread;

import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;

public class ABCAlternate {

    public static void main(String[] args) {
        Alternate alternate = new Alternate();

        new Thread(new Runnable() {
            @Override
            public void run() {
                for (int i=0;i<20;i++){
                    alternate.printA(i);
                }
            }
        },"A").start();
        new Thread(new Runnable() {
            @Override
            public void run() {
                for (int i=0;i<20;i++){
                    alternate.printB(i);
                }
            }
        },"B").start();
        new Thread(new Runnable() {
            @Override
            public void run() {
                for (int i=0;i<20;i++){
                    alternate.printC(i);
                }
            }
        },"C").start();
    }

}
class Alternate{

    private int number = 1;

    private Lock lock = new ReentrantLock();//锁

    private Condition condition1 = lock.newCondition();
    private Condition condition2 = lock.newCondition();
    private Condition condition3 = lock.newCondition();


    public void printA(int totalLoop){

        lock.lock();//加锁

        try{
            if (number != 1){
                condition1.await();
            }
            System.out.println(Thread.currentThread().getName() + " == \tA\t" + "第" + totalLoop + "次循环");

            number = 2;
            condition2.signal();//唤醒2
        } catch (InterruptedException e) {
            e.printStackTrace();
        } finally {
            lock.unlock();//释放锁
        }

    }

    public void printB(int totalLoop){

        lock.lock();//加锁

        try{
            if (number != 2){
                condition2.await();
            }
            System.out.println(Thread.currentThread().getName() + " == \tB\t" + "第" + totalLoop + "次循环");

            number = 3;
            condition3.signal();//唤醒3
        } catch (InterruptedException e) {
            e.printStackTrace();
        } finally {
            lock.unlock();//释放锁
        }

    }
    public void printC(int totalLoop){

        lock.lock();//加锁

        try{
            if (number != 3){
                condition3.await();
            }
            System.out.println(Thread.currentThread().getName() + " == \tC\t" + "第" + totalLoop + "次循环");

            number = 1;
            condition1.signal();//唤醒1
        } catch (InterruptedException e) {
            e.printStackTrace();
        } finally {
            lock.unlock();//释放锁
        }

    }


}