Thread forced join, thread forced join application scenarios

Thread forced join join

• join Merge threads , After this thread has finished executing , Execute other threads , Other threads are blocking
• Thread queue jumping
• In the code block of the main thread , If you come across join Method , At this time, the main thread will block , Wait for the child thread to end , And go on with it join Code block after

Code

package testthread;

public class TestJoin {
    

    public static void main(String[] args) throws InterruptedException {
    

        // Start thread 
        Thread t = new Thread("vip") {
    
            @Override
            public void run() {
    
                int countDown = 10;
                while (true) {
    
                    try {
    
                        Thread.sleep(1000);
                    } catch (InterruptedException e) {
    
                        e.printStackTrace();
                    }
                    countDown--;
                    System.out.println(Thread.currentThread().getName() + System.currentTimeMillis());
                    if (countDown <= 0) {
    
                        break;
                    }
                }
            }
        };

        //t coming , But not yet join, here , It is the main thread and t Threads execute alternately 
        t.start();

        // The main thread 
        for (int i = 0; i < 20; i++) {
    
            if (i == 10) {
    
                t.join();// perform join Instead of alternate execution , Main thread blocking , Only execute t Threads , After execution, execute the main thread 
            }
            System.out.println("main" + System.currentTimeMillis());
        }
    }
    
    /*  Output ： main1644572688188 main1644572688188 main1644572688188 main1644572688188 main1644572688188 main1644572688188 main1644572688188 main1644572688188 main1644572688188 main1644572688188 vip1644572689190 vip1644572690191 vip1644572691206 vip1644572692217 vip1644572693224 vip1644572694239 vip1644572695250 vip1644572696264 vip1644572697264 vip1644572698277 main1644572698278 main1644572698278 main1644572698278 main1644572698278 main1644572698278 main1644572698278 main1644572698278 main1644572698278 main1644572698278 main1644572698278 */
}