How to check a thread has stopped or not in Java

Problem Description

How to check a thread has stopped or not?

Solution

Following example demonstrates how to check a thread has stop or not by checking with isAlive() method.

public class Main {
   public static void main(String[] argv)throws Exception { 
      Thread thread = new MyThread();
      thread.start();
      
      if (thread.isAlive()) {
         System.out.println("Thread has not finished");
      } else {
         System.out.println("Finished");
      }
      long delayMillis = 5000; 
      thread.join(delayMillis);
      
      if (thread.isAlive()) {
         System.out.println("thread has not finished");
      } else {
         System.out.println("Finished");
      }
      thread.join();
   }
}
class MyThread extends Thread {
   boolean stop = false;
   public void run() {
      while (true) {
         if (stop) {
            return;
         }
      }
   }
}

Result

The above code sample will produce the following result.

Thread has not finished
Finished