java多线程编程（打印三个线程名5次ABCABCABCABCABC）

1.题目描述

启动三个线程，三个线程名称分别是A,B,C；每个线程将自己的名称在屏幕上打印5遍，打印顺序是ABCABCABCABCABC

2.解题思路

2.1写打印A、B、C的方法

//设置标记位，判断应该打印哪个线程名
    private int flag = 1;
//记录打印次数
    private int count = 1；
//打印线程名称A方法
//    顺序打印，用锁
    public synchronized void PrintA(){
//    如果falg不为1，等待
        while (flag != 1){
            try {
                wait();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
//    打印当前线程名
        System.out.print(Thread.currentThread().getName());
//    使其可以进入打印线程B方法
        flag = 2;
        notifyAll();
//    打印次数+1
        count++;
    }
//打印线程名称B方法
    public synchronized void PrintB(){
        while (flag != 2){
            try {
                wait();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
        System.out.print(Thread.currentThread().getName());
        flag = 3;
        notifyAll();
        count++;
    }
//打印线程名称C方法
    public synchronized void PrintC(){
        while (flag != 3){
            try {
                wait();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
        System.out.print(Thread.currentThread().getName());
        flag = 1;
        notifyAll();
        count++;
    }

2.2写MyThread类调用三个打印方法

class MyThread implements Runnable{
    public PrintTest1 printTest1;
    public MyThread(PrintTest1 printTest1){
        this.printTest1 = printTest1;
    }
    @Override
    public void run() {
//    因为最后一次打印A时count=13
        while(printTest1.getCount()<14){
            if(Thread.currentThread().getName().equals("A")){
                printTest1.PrintA();
            }
            if(Thread.currentThread().getName().equals("B")){
                printTest1.PrintB();
            }
            if(Thread.currentThread().getName().equals("C")){
                printTest1.PrintC();
            }
        }
    }
}

3.整体代码如下

/**
 * 2.启动三个线程，三个线程名称分别是A,B,C；
 * 每个线程将自己的名称在屏幕上打印5遍，打印顺序是ABCABCABCABCABC
 */
class PrintTest1{
    private int flag=1;
    private int count=1;
    public int getCount(){
        return count;
    }
    public synchronized void PrintA(){
        while (flag != 1){
            try {
                wait();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
        System.out.print(Thread.currentThread().getName());
        flag = 2;
        notifyAll();
        count++;
    }
    public synchronized void PrintB(){
        while (flag != 2){
            try {
                wait();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
        System.out.print(Thread.currentThread().getName());
        flag = 3;
        notifyAll();
        count++;
    }
    public synchronized void PrintC(){
        while (flag != 3){
            try {
                wait();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
        System.out.print(Thread.currentThread().getName());
        flag = 1;
        notifyAll();
        count++;
    }

}

class MyThread implements Runnable{
    public PrintTest1 printTest1;
    public MyThread(PrintTest1 printTest1){
        this.printTest1 = printTest1;
    }
    @Override
    public void run() {
        while(printTest1.getCount()<14){
            if(Thread.currentThread().getName().equals("A")){
                printTest1.PrintA();
            }
            if(Thread.currentThread().getName().equals("B")){
                printTest1.PrintB();
            }
            if(Thread.currentThread().getName().equals("C")){
                printTest1.PrintC();
            }
        }
    }
}
public class Test2 {
    public static void main(String[] args) {
        PrintTest1 printTest1 = new PrintTest1();
        MyThread myThread = new MyThread(printTest1);
        new Thread(myThread,"A").start();
        new Thread(myThread,"B").start();
        new Thread(myThread,"C").start();
    }
}

4.运行结果