Thread.sleep pausing whole program

Question

I have a main form with a button, that when pressed, should start a new count-down timer thread.

This is the code in the button's action listener:

 Counter c = new Counter(timeToFinish);

This is the code for the Counter class:

class Counter implements Runnable {

        int waitingTime = 0;
        Thread myCounter = new Thread(this);

        public Counter(int waitingTime)
        {
            this.waitingTime = waitingTime;
            myCounter.run();
        }

        public void run(){

            //Start countdown:
            do  
            {

                waitingTime -= 1;

                try {

                    Thread.sleep(1000);
                    System.out.println(waitingTime);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            } while (waitingTime >= 0);

        }
    }

The problem is, when I create a new instance of the Counter class, it pauses the whole program, not just that thread. The problem must be with "Thread.sleep".

Answer 1

Because you are directly calling the run method.

Instead you should wrap it in a Thread and start the thread.

For eg, replace

myCounter.run();

by

new Thread(this).start();

Answer 2

Just because you call the run method from the Counter constructor. That's not how it works with threads. You'll have to remove this call, wrap the Runnable in a Thread instance and call start() on the thread:

 new Thread(new Counter(2)).start();

Answer 3

You aren't actually start() ing multiple threads.

The Thread.run() method simply runs the code associated with the thread, like any other normal function. It doesn't start a separate thread.

You need to call Thread.start() , to start a new thread and run your code in it.

Answer 4

You should use start() method of your thread. Use

c.start();

otherwise you have a class and you are invoking one of its methods, and of course it is running in main thread and sleeping the main thread.

Answer 5

You're calling run directly, it'll run in the current thread, and sleep the current thread, which I guess is the event thread. This cause the pause in your program.

Answer 6

You should use SwingUtilities class

see

http://www.java2s.com/Code/Java/Threads/InvokeExampleSwingandthread.htm

    // Report the result using invokeLater().
    SwingUtilities.invokeLater(new Runnable() {
      public void run() {
        resultLabel.setText("Ready");
        setEnabled(true);
      }
    });
  }
};