ABC三个线程交替打印10遍，要求A打印5次，B打印10次，C打印15次

问题：

　　ABC三个线程交替打印10遍，要求A打印5次，B打印10次，C打印15次，

 第一遍
 AAAAABBBBBBBBBBCCCCCCCCCCCCCCC
 第二遍
 AAAAABBBBBBBBBBCCCCCCCCCCCCCCC
...共打印10遍

1.使用Sychronized+wait()+notify()的方式

package com.yang.test;

/**
 * ABC三个线程交替打印10遍，要求A打印5次，B打印10次，C打印15次
 * 第一遍
 * AAAAABBBBBBBBBBCCCCCCCCCCCCCCC
 * 第二遍
 * AAAAABBBBBBBBBBCCCCCCCCCCCCCCC
 * ...共打印10遍
 * @author yang yajun
 * @date 2020/12/2615:31
 */
public class OrderThreadPrint {

    public static void main(String[] arg0){
        Print print = new Print();

        new Thread(()->{
            for (int i = 0; i < 10; i++) {
                print.printA();
            }
        },"A").start();
        new Thread(()->{
            for (int i = 0; i < 10; i++) {
                print.printB();
            }
        },"B").start();
        new Thread(()->{
            for (int i = 0; i < 10; i++) {
                print.printC();
            }
        },"C").start();
    }
}

class Print{
    private int i = 1;
    public synchronized void  printA(){
        while (i%3!=1) {
            try {
                wait();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
        for (int j = 0; j < 5; j++) {
            System.out.print(Thread.currentThread().getName() + i);
        }
        i++;
        notifyAll();
    }
    public synchronized void  printB(){
        while (i%3!=2) {
            try {
                wait();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
        for (int j = 0; j < 10; j++) {
            System.out.print(Thread.currentThread().getName()+i);
        }
        i++;
        notifyAll();
    }
    public synchronized void  printC(){
        while (i%3!=0) {
            try {
                wait();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
        for (int j = 0; j < 15; j++) {
            System.out.print(Thread.currentThread().getName() + i);
        }
        i++;
        notifyAll();
    }

}

2.使用Lock(Condition)+await()+signal()来实现

package com.yang.test;

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

/**
 * ABC三个线程交替打印10遍，要求A打印5次，B打印10次，C打印15次
 * 第一遍
 * AAAAABBBBBBBBBBCCCCCCCCCCCCCCC
 * 第二遍
 * AAAAABBBBBBBBBBCCCCCCCCCCCCCCC
 * ...共打印10遍
 * @author yang yajun
 * @date 2020/12/2615:31
 */
public class OrderThreadPrintLock {

    public static void main(String[] arg0){
        PrintLk print = new PrintLk();

        new Thread(()->{
            for (int i = 0; i < 10; i++) {
                print.printA();
            }
        },"A").start();
        new Thread(()->{
            for (int i = 0; i < 10; i++) {
                print.printB();
            }
        },"B").start();
        new Thread(()->{
            for (int i = 0; i < 10; i++) {
                print.printC();
            }
        },"C").start();
    }
}

class Print{
    private int i = 1;
    private Lock lock = new ReentrantLock();
    private Condition condition1 = lock.newCondition();
    private Condition condition2 = lock.newCondition();
    private Condition condition3 = lock.newCondition();

    public synchronized void  printA(){
        lock.lock();
        try {
            while (i!=1) {//判断，多线程通信，使用while代替if
                try {
                    condition1.await();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
　　　　　　　　//干活
            for (int j = 0; j < 5; j++) {
                System.out.print(Thread.currentThread().getName() + i);
            }
            i=2;
            condition2.signal();//通知
        }finally {
            lock.unlock();
        }

    }
    public synchronized void  printB(){
        lock.lock();
        try {
            while (i!=2) {
                try {
                    condition2.await();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
            for (int j = 0; j < 10; j++) {
                System.out.print(Thread.currentThread().getName()+i);
            }

            i=3;
            condition3.signal();
        }finally {
            lock.unlock();
        }
    }
    public synchronized void  printC(){
        lock.lock();
        try {
            while (i!=3) {
                try {
                    condition3.await();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
            for (int j = 0; j < 15; j++) {
                System.out.print(Thread.currentThread().getName() + i);
            }
            i=1;
            condition1.signal();
        }finally {
            lock.unlock();
        }
    }

}

 总结：使用Synchronized和Lock都能实现，而Lock的优势是可以精准唤醒，不像Synchronized的只能notifyAll()