We can use join() method for this purpose. On calling join() method,

current thread waits for the child thread to which it joins to finish.

Sample code is as follows:

Thread myThread = new Thread(new Runnable() {

public void run() {

}

});

myThread.start();

// Join on myThread

myThread.join()

https://www.demo2s.com/java/java-interview-question-parent-thread-waits-for-termination-of-child-t.html