How to create a simple digital timer using Java

To create a simple digital timer in Java, we can use javax.swing for the GUI components and java.util.Timer or javax.swing.Timer for the timer functionality. Below is an easy method to create a basic digital timer that counts up in seconds.

Simple Digital Timer in Java:

This example uses javax.swing.Timer because it’s straightforward and integrates well with the Swing GUI, handling the event dispatch thread correctly.

• Create a new Java file: Name it SimpleDigitalTimer.java.
• Add the following code:

  import javax.swing.*;
  import java.awt.*;
  import java.awt.event.ActionEvent;
  import java.awt.event.ActionListener;
  
  public class SimpleDigitalTimer extends JFrame {
      private int seconds = 0;
      private JLabel timeLabel;
      private Timer timer;
  
      public SimpleDigitalTimer() {
          // Set up the frame
          setTitle("Simple Digital Timer");
          setSize(300, 150);
          setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
          setLocationRelativeTo(null);
          
          // Initialize the time label
          timeLabel = new JLabel("Time: 0 s", SwingConstants.CENTER);
          timeLabel.setFont(new Font("Arial", Font.BOLD, 30));
          add(timeLabel, BorderLayout.CENTER);
  
          // Create a timer that updates every 1000 milliseconds (1 second)
          timer = new Timer(1000, new ActionListener() {
              @Override
              public void actionPerformed(ActionEvent e) {
                  seconds++;
                  timeLabel.setText("Time: " + seconds + " s");
              }
          });
  
          // Create start and stop buttons
          JPanel buttonPanel = new JPanel();
          JButton startButton = new JButton("Start");
          JButton stopButton = new JButton("Stop");
  
          startButton.addActionListener(new ActionListener() {
              @Override
              public void actionPerformed(ActionEvent e) {
                  timer.start();
              }
          });
  
          stopButton.addActionListener(new ActionListener() {
              @Override
              public void actionPerformed(ActionEvent e) {
                  timer.stop();
              }
          });
  
          buttonPanel.add(startButton);
          buttonPanel.add(stopButton);
          add(buttonPanel, BorderLayout.SOUTH);
      }
  
      public static void main(String[] args) {
          // Run the GUI in the Event Dispatch Thread
          SwingUtilities.invokeLater(new Runnable() {
              @Override
              public void run() {
                  SimpleDigitalTimer timer = new SimpleDigitalTimer();
                  timer.setVisible(true);
              }
          });
      }
  }
  

  Key Points:

• GUI Setup: The timer uses JFrame to display a window, with a central JLabel showing the time in seconds.
• Timer: javax.swing.Timer is used to increment the seconds every 1 second (1000 milliseconds).
• Buttons: Start and Stop buttons are provided to control the timer.
• Thread Safety: The GUI runs on the Event Dispatch Thread using SwingUtilities.invokeLater.

• Running the Program:

• Save the code in a file named SimpleDigitalTimer.java.
• Compile the program using:

  javac SimpleDigitalTimer.java
  

  Run the program using:

  java SimpleDigitalTimer
  

  This will open a simple GUI with a timer that counts seconds, with options to start and stop the timer.