How to Make a Timer in Java

This tutorial is a guide to using the timer found in the Swing class of the Java programmer language, beginning with an explanation of timer methods and concluding with a complete program that illustrates basic use of the timer object. Timers can be used to specify a future action or for timing dependent or repeated activities such as animation. The unit of time used by the timer object is milliseconds.

Things You'll Need

• Java Standard Development Kit (SDK)
• Java Integrated Development Environment (IDE)

Instructions

1. Create a timer object: Timer (delay in milliseconds, Action listener). For example:
   private Timer timer1 = new Timer(1500, this);

2. An optional initial delay can be set. This delay will occur once after the timer is started. For example:
   timer1.setInitialDelay(5000);

3. Start timer. For example:
   timer1.start();

4. Specify the action to be performed at the timer's intervals in the actionPerformed() method. For example:
   public void actionPerformed(ActionEvent e) {
   //action to perform code
   }

5. Stop timer. For example:
   timer1.stop();

6. The following code is a simple working example of how to use a timer to create a continuous drawing of ovals that increase in size and descend vertically down the window.

   public class TimerMain {
   //main function instantiates TimerExample object
   public static void main(String[] args){
   TimerExample display = new TimerExample();
   }
   }

   //imports for TimerExample class:
   import java.awt.event.ActionEvent;
   import java.awt.event.ActionListener;
   import java.awt.*;
   import javax.swing.*;
   public class TimerExample extends JFrame implements ActionListener {
   private JPanel container;
   JLabel labelCounter;
   private Timer timer1 = new Timer(250, this);
   int w,x,y,z = 1;
   public TimerExample() {
   //set initial delay to 1000 milliseconds
   timer1.setInitialDelay(1150);

   //initialize window
   container = new JPanel();
   this.add(container);
   this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
   setSize(200,200);
   this.setVisible(true);

   //start timer
   timer1.start();
   }
   /**
   * when timer begins this method draws ovals that increase in size
   * and descend vertically down the window
   */
   public void actionPerformed(ActionEvent e) {
   if (z < 100){
   Graphics g = container.getGraphics();
   g.drawOval(w,x,y,z);
   w = w+2;
   x = x+2;
   y = y+2;
   z = z+2;
   }
   else //stop timer (and drawing) when z coordinate is greater than 99
   timer1.stop();
   }
   }

References

• Java Foundation Classes in a Nutshell, Flanagan, David, 1999.

Resources

• Read this Article in Spanish