Digital Clock Using Swing in Java

Introduction

This article describes the creation of a digital clock using Java. This application shows the system's current time.

Packages Imported

import javax.swing.JFrame

Jframe is an extended version of Frame that supports the Swing component architecture.

import java.awt.Color

The Format RGB shows the combination of red, green and blue color, and its value ranges between 0 and 255.

import javax.swing.WindowConstants

WindowConstants is used for operations like window closing and so on.

Syntax

public class DimensionDemo extends Object class

import java.awt.event.ActionEvent

It imports only the "ActionEvent" class.

import java.awt.event.ActionListener

An action event is fired, whenever any action is done by the user.

import java.util.Calendar

The class java.util.Date defines an instance of time.

import java.awt.Graphics

Graphics exists under the class that extends Object. Graphics is used to represent graphics on the window.

Syntax

public class GraphicsDemo extends Object

import java.awt.Dimension

Dimension is a class that extends the Object class.

import javax.swing.JPanel

JPanel can be used in place of Canvas. The new feature of JPanel is Border.

import javax.swing.Timer;

A Swing timer fires one or more action events after a specified delay.

import java.awt.Font

Font is a class that represents fonts and it implements the serializable interface.

Syntax

public class FontDemo implements Serializable interface

Coding

import java.awt.*; 
//In place of star we use Color,Dimension,Font,Graphics,event.ActionEvent,event.ActionListner. 
import java.util.*;
//In place of star we use Calendar. 
import javax.swing.*;
//In place of star we use Jframe.JPane1,WindowConstants.
import java.awt.event.ActionListener;
import javax.swing.Timer;
import java.awt.event.ActionEvent;
public class DigitalClock1
  {
    public static void main(String[] args)
      {
        JFrame frm = new JFrame();
        frm.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
        SimpleDigitalClock clock1 = new SimpleDigitalClock();
        frm.add(clock1);
        frm.pack();
        frm.setVisible(true);
      } 
   static class SimpleDigitalClock extends JPanel
     { 
       String stringTime;
       int hour, minute, second;
       String aHour = "";
       String bMinute = "";
       String cSecond = ""; 
       public void setStringTime(String abc)
         {
           this.stringTime = abc;
         } 
       public int Number(int a, int b)
         {
           return (a <= b) ? a : b;
         } 
       SimpleDigitalClock()
         { 
           Timer t = new Timer(1000, new ActionListener()
             { 
               public void actionPerformed(ActionEvent e)
                 {
                   repaint();
                 }
             });
           t.start();
         }
      @Override 
      public void paintComponent(Graphics v)
        {
          super.paintComponent(v);
          Calendar rite = Calendar.getInstance();
          hour = rite.get(Calendar.HOUR_OF_DAY);
          minute = rite.get(Calendar.MINUTE);
          second = rite.get(Calendar.SECOND);
          if (hour < 10)
            {
              this.aHour = "0"; 
            } 
          if (hour >= 10)
            {
              this.aHour = "";
            } 
          if (minute < 10)
            {
              this.bMinute = "0";
            } 
          if (minute >= 10)
            {
              this.bMinute = "";
            }
          if (second < 10)
            {
              this.cSecond = "0";
            }
          if (second >= 10)
            {
              this.cSecond = "";
            } 
          setStringTime(aHour + hour + ":" + bMinute+ minute + ":" + cSecond + second);
          v.setColor(Color.BLACK);
          int length = Number(this.getWidth(),this.getHeight());
          Font Font1 = new Font("SansSerif", Font.PLAIN, length / 5);
          v.setFont(Font1);
          v.drawString(stringTime, (int) length/6, length/2);
        } 
      @Override 
      public Dimension getPreferredSize()
        {
          return new Dimension(200, 200);
        }
      }
   }

  Output