Digital Watch in Java Swing

Introduction

Java Swing is a Java GUI widget toolkit that comes with various useful widgets. It is a part of the Java Foundation Classes(JFC). JFC contains many packages for creating desktop applications.

We can also use Java Swing to create a Digital clock.

Java Swing Program to create a Digital watch

We will use the following Java packages:

• swing package
• awt package
• A util package
• The text package

Algorithm

• To create a frame, we must first import the swing package. 
• Then, the util package will be used to build the user interface. 
• We also use a text package to write the program where date-time is required.
• We first create a frame and define its dimensions. 
• We then set the values of all the variables to zero and initialize the three variables Hours, Minutes, and Seconds.
• In this software, the Calendar class is used. The abstract class that gives us access to date, time, year, and month methods is the Java Calendar class.
• The millisecond interval is provided by Sleep(1000).
   

// Java program to create digital watch
import javax.swing.*;  
import java.awt.*;  
import java.text.*;  
import java.util.*;  


public class DigitalWatch implements Runnable{  


JFrame frame;  
Thread thread=null;  
int hours=0, minutes=0, seconds=0;  
String timeString = "";  
JButton button;  
  
DigitalWatch(){  
    frame=new JFrame();  
      
    thread = new Thread(this);  
        thread.start();  
      
    button=new JButton();  
        button.setBounds(100,100,100,50);  
      
    frame.add(button);  
    frame.setSize(300,400);  
    frame.setLayout(null);  
    frame.setVisible(true);  
}  
  
 public void run() {  
      try {  
         while (true) {  
  
            Calendar cal = Calendar.getInstance();  
            hours = cal.get( Calendar.HOUR_OF_DAY );  
            if ( hours > 12 )
            {hours -= 12;}  
            minutes = cal.get( Calendar.MINUTE );  
            seconds = cal.get( Calendar.SECOND );  
  
            SimpleDateFormat formatter = new SimpleDateFormat("hh:mm:ss");  
            Date date = cal.getTime();  
            timeString = formatter.format(date);  
  
            printTime();  
  
            thread.sleep(1000); //in milliseconds  
         }  
      }  
      catch (Exception e) { }  
 }  
  
  public void printTime(){  
    button.setText(timeString);  
  }  
  
  public static void main(String[] args) {  
    new DigitalWatch();  
  }  
}  

You can also try this code with Online Java Compiler

Run Code

The output of the program

Read also Swing components in java