Learn how to create a real-time digital clock using Java. This program will display the current time and update it every second.

Code Implementation

public class DigitalClock {
    public static void main(String[] args) {
        // Create an instance of the ClockFrame class
        ClockFrame clockFrame = new ClockFrame();
    }
}

import javax.swing.*;
import java.awt.*;
import java.text.SimpleDateFormat;
import java.util.Date;

class ClockFrame extends JFrame {
    private JLabel timeLabel;

    public ClockFrame() {
        setTitle("Digital Clock");
        setSize(400, 200);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        timeLabel = new JLabel("", JLabel.CENTER);
        timeLabel.setFont(new Font("Serif", Font.BOLD, 50));
        add(timeLabel);

        setVisible(true);

        // Update time every second
        Timer timer = new Timer(1000, e -> updateClock());
        timer.start();
    }

    private void updateClock() {
        SimpleDateFormat dateFormat = new SimpleDateFormat("HH:mm:ss");
        String currentTime = dateFormat.format(new Date());
        timeLabel.setText(currentTime);
    }
}
        

Explanation of the Program

This Java program creates a simple graphical user interface (GUI) digital clock using the javax.swing library.

• ClockFrame class: This class extends JFrame to create a window with a JLabel where the time is displayed. It also sets up the timer to update the time every second.
• Timer: The Timer class calls the updateClock() method every 1000 milliseconds (1 second) to refresh the displayed time.
• SimpleDateFormat: This is used to format the current time into a string in the format “HH:mm:ss”.

How to Run the Program

1. Ensure that you have Java Development Kit (JDK) installed on your system.
2. Create a new file called DigitalClock.java and paste the code into the file.
3. Open a terminal or command prompt, navigate to the directory where the file is located, and compile the program using the following command:

   javac DigitalClock.java

4. Run the program using the following command:

   java DigitalClock

5. The digital clock window will appear showing the current time, updating every second.