Beginner's Guide to Building a Digital Clock in Java

Here's a simple digital clock implemented in Java using the Swing framework. The clock updates every second and displays the current time in hours, minutes, and seconds format.

Code:

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

public class DigitalClock extends JFrame {

private JLabel timeLabel;

public DigitalClock() {
// Setting up the frame
setTitle("Digital Clock");
setSize(300, 150);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setLocationRelativeTo(null);

// Adding a label to display time
timeLabel = new JLabel();
timeLabel.setFont(new Font("Arial", Font.PLAIN, 48));
timeLabel.setHorizontalAlignment(SwingConstants.CENTER);

// Adding the label to the frame
add(timeLabel);

// Timer to update the clock every second
Timer timer = new Timer(1000, e -> updateClock());
timer.start();
}

// Method to update the clock every second
private void updateClock() {
// Get the current time
SimpleDateFormat sdf = new SimpleDateFormat("HH:mm:ss");
String currentTime = sdf.format(new Date());

// Update the label with the new time
timeLabel.setText(currentTime);
}

public static void main(String[] args) {
// Create and show the digital clock
SwingUtilities.invokeLater(() -> {
DigitalClock clock = new DigitalClock();
clock.setVisible(true);
});
}
}

Explanation:

• JFrame: The main window of the clock, where the time is displayed.
• JLabel: A label component is used to show the current time. The text is updated every second.
• SimpleDateFormat: Used to format the current time in HH:mm:ss format (hours:minutes:seconds).
• Timer: The javax.swing.Timer object is set to call the updateClock() method every 1000 milliseconds (1 second).
• Font: The time is displayed in a large font (48 size), which can be adjusted for your preference.

How to run the code:

1. Copy and paste the code into a .java file (for example, DigitalClock.java).
2. Compile and run the file using a Java IDE or command line:
   • To compile: javac DigitalClock.java
   • To run: java DigitalClock

Once you run the program, it will show a window with the current time updating every second.