CODEWITHSUNDEEP
javamultithreading
qqibrow
qqibrow

Reputation: 3022

child thread blocks parent thread in java

   public static void main(String[] args) throws Exception {
    new Thread(new Runnable() {
        public void run() {
            while(true) {
                try {
                    Thread.sleep(1000);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                System.out.println("Hello");
            }
        }
    }).run();
    System.out.println("Bye");
}

In the main thead, I create a new thread, which will print "hello" every second. Why the final "Bye" never got print? In the other word, why the child thread blocks the main thread?

Upvotes: 1

Views: 802

Answers (1)

Reinstate Monica
Reinstate Monica

Reputation: 2798

Because you are calling run(), instead of start().

You must never call run() directly. If you call start(), the program will call run() for you, in a different thread. (Like you wanted.) By calling run() yourself, you are going into the run() method with the parent thread, and get stuck in an eternal loop, with your parent thread.

Upvotes: 9

Related Questions