两个线程交替打印奇偶

要求描述

两个线程，其中一个线程打印奇数，另外一个线程打印偶数。两个线程交替打印，输入1,2,3，...，100

基本思路

利用通知等待机制，第一个线程打印后，然后唤醒第二个线程，并释放锁。第二个线程执行同样的操作

代码实现 

package basicKnowledge.thread;

import java.util.concurrent.atomic.AtomicInteger;

/**
 * @基本功能:线程交替打印输出奇偶
 * @program:summary
 * @author:peicc
 * @create:2019-09-26 09:11:15
 **/
public class ThreadPrint {
    static  Object object=new Object();

    public static void main(String[] args) {
        Thread thread1=new Thread(new Runnable() {
            @Override
            public void run() {
                synchronized (object){
                    for (int i = 1; i <100 ; i+=2) {
                        System.out.println(Thread.currentThread().getName()+": "+i);
                        object.notify();//唤醒其他线程
                        try {
                            object.wait();
                        }
                        catch (InterruptedException e) {
                            e.printStackTrace();
                        }
                    }
                }
            }
        },"打印奇数线程");
        Thread thread2=new Thread(new Runnable() {
            @Override
            public void run() {
                synchronized (object){
                    for (int i = 2; i <=100 ; i+=2) {
                        System.out.println(Thread.currentThread().getName()+": "+i);
                        object.notify();//唤醒其他线程
                        try {
                            object.wait();
                        }
                        catch (InterruptedException e) {
                            e.printStackTrace();
                        }
                    }
                }
            }
        },"打印偶数线程");
        thread1.start();
        thread2.start();
    }


}

 输出结果（后面的省略）

打印奇数线程: 1
打印偶数线程: 2
打印奇数线程: 3
打印偶数线程: 4
打印奇数线程: 5
打印偶数线程: 6
打印奇数线程: 7
打印偶数线程: 8
打印奇数线程: 9
打印偶数线程: 10

上述方法基本解决了我们的需求，但是有个问题，很严重，那就是打印结束后打印偶数的线程再次进入了等待状态，整个程序无法终止。

 代码升级版

package leetcode;

/**
 * @基本功能:两个线程交替执行，一个输出偶数，一个输出奇数
 * @program:summary
 * @author:peicc
 * @create:2019-07-29 12:56:49
 **/
//线程执行完毕如何终止？
public class ThreadTurn {
     static Object o=new Object();
    static boolean flag=false;//标志位


    public static void main(String[] args) {
        ThreadTurn threadTurn=new ThreadTurn();
        Thread oddThread=new Thread(new Runnable() {
            @Override
            public void run() {
                synchronized (threadTurn){
                    for (int i = 1; i <100 ; ) {
                        if(!flag){
                            System.out.println("打印奇数线程"+i);
                            threadTurn.notify();//唤醒等待线程
                            flag=true;
                            i+=2;
                        }else{
                            try {
                                threadTurn.wait();
//                            Thread.sleep(100);
                            }
                            catch (InterruptedException e) {
                                e.printStackTrace();
                            }
                        }
                    }

                }

            }
        },"奇数线程");
        Thread evenThread=new Thread(new Runnable() {
            @Override
            public void run() {
                synchronized (threadTurn){
                    for (int i = 2; i <= 100; ) {
                        if(flag){
                            System.out.println("打印偶数线程"+i);
                            threadTurn.notify();//唤醒等待线程
                            flag=false;
                            i+=2;
                        }else{
                            try {
                                threadTurn.wait();
//                            Thread.sleep(100);
                            }
                            catch (InterruptedException e) {
                                e.printStackTrace();
                            }
                        }


                    }
                }
            }
        },"偶数线程");
        evenThread.start();
        oddThread.start();

    }
}

补充练习

两个线程，其中一个线程打印数字，另外一个线程打印字母。两个线程交替打印，输入1,2,a,3,4,b,5,6,c

package basicKnowledge.thread;

/**
 * @基本功能:两个线程交替执行，一个输出偶数，一个输出奇数
 * @program:summary
 * @author:peicc
 * @create:2019-07-29 12:56:49
 **/
//线程执行完毕如何终止？
public class ThreadPrint2 {
     static Object o=new Object();
    static boolean flag=true;//标志位


    public static void main(String[] args) {
        ThreadPrint2 threadTurn=new ThreadPrint2();
        Thread oddThread=new Thread(new Runnable() {
            @Override
            public void run() {
                synchronized (threadTurn){
                    int count=0;
                    for (int i = 1; i <=52 ; ) {
                        if(count<2){
                            System.out.println("打印数字线程"+i);
                            threadTurn.notify();//唤醒等待线程
                            count++;
                            i++;
                        }else{
                            try {

                                count=0;
                                threadTurn.wait();
//                            Thread.sleep(100);
                            }
                            catch (InterruptedException e) {
                                e.printStackTrace();
                            }
                        }
                    }

                }

            }
        },"奇数线程");
        Thread evenThread=new Thread(new Runnable() {
            @Override
            public void run() {
                synchronized (threadTurn){
                    for (int i = 0; i <26; ) {
                        if(flag){
                            System.out.println("打印字母线程"+(char)(i+'a'));
                            threadTurn.notify();//唤醒等待线程
                            flag=false;
                            i++;
                        }else{
                            try {

                                flag=true;
                                threadTurn.wait();
//                            Thread.sleep(100);
                            }
                            catch (InterruptedException e) {
                                e.printStackTrace();
                            }
                        }


                    }
                }
            }
        },"偶数线程");
        oddThread.start();
        evenThread.start();


    }
}