多线程顺序执行问题

编写一个程序，开启3个线程，这3个线程的ID分别为A、B、C，每个线程将自己的ID在屏幕上打印10遍，要求输出结果必须按ABC的顺序显示；如：ABCABC….依次递推。

1、线程未加顺序执行程序

package com.pertops.route;

public class ThreadTemplate {

    public static void main(String[] args) {
        for(int i=0;i<10;i++){
            new Thread(new Runnable() {         
                @Override
                public void run() {
                    sysThreadName();
                }
            }, "A").start();
            new Thread(new Runnable() {         
                @Override
                public void run() {
                    sysThreadName();
                }
            }, "B").start();        
            new Thread(new Runnable() {         
                @Override
                public void run() {
                    sysThreadName();
                }
            }, "C").start();            
        }

    }
    
    static public void sysThreadName(){
        System.out.print(Thread.currentThread().getName());
    }
}

15280d70649a94fd4915716b1cfeeea.png

当上面这段代码敲完运行后并会发现线程输出时是无序的~换个角度思考一下如何使这些线程按人为所期望的顺序执行呢？

使用线程的join方法，该方法的作用是“等待线程执行结束”，即join()方法后面的代码块都要等待现场执行结束后才能执行

2、线程添加顺序执行程序

package com.pertops.route;

public class ThreadTemplate2 {
    
    public static void main(String[] args) throws InterruptedException {
        for(int i=0;i<10;i++){
            Thread thread1 =  new Thread(new Runnable() {           
                @Override
                public void run() {
                    sysThreadName();
                }
            }, "A");
            
            Thread thread2 = new Thread(new Runnable() {            
                @Override
                public void run() {
                    sysThreadName();
                }
            }, "B");    
            
            Thread thread3 = new Thread(new Runnable() {            
                @Override
                public void run() {
                    sysThreadName();
                }
            }, "C");
            
            thread1.start();
            //thread1.sleep(100);
            thread1.join();
            
            thread2.start();
            //thread2.sleep(100);
            thread2.join();
            
            thread3.start();
            thread3.join();
            //thread3.sleep(100);
        
        }

    }
    
    static public void sysThreadName(){
        System.out.print(Thread.currentThread().getName()+"--");
    }
}

f34a184a5e78fd5ab4011d388ae58e8.png