无法在[java]中执行计时器

Question

I've been trying to get down the basics of using a timer so that I can create a bouncing ball program, but I can't seem to implement a timer correctly. This program should in theory just continuously print the display, but instead the program simply terminates. What can I do to remedy this issue and fix the timer?

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.Timer;
import javax.swing.JFrame;


public class DisplayStuff {

public static void main(String[] args) {


    class TimerListener implements ActionListener
    {
        public void actionPerformed(ActionEvent event)
        {
            System.out.println("Display me.");
        }
    }

    ActionListener listener = new TimerListener();
    Timer t= new Timer(1000, listener);
    t.start();

}
}

Answer 1

Your program has no Swing event thread with which to continue the Timer. You need to put it into a visualized Swing GUI to start the Swing event dispatch thread, and then start the timer. This could be achieved by something as simple as displaying a JOptionPane:

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JOptionPane;
import javax.swing.Timer;
import javax.swing.JFrame;

public class DisplayStuff {

   public static void main(String[] args) {

      class TimerListener implements ActionListener {
         public void actionPerformed(ActionEvent event) {
            System.out.println("Display me.");
         }
      }

      ActionListener listener = new TimerListener();
      Timer t = new Timer(1000, listener);
      t.start();

      // ***** add just this *****
      JOptionPane.showMessageDialog(null, "foo");

   }
}