Here is a piece of code to build a Java clock, that uses threads, gets the data for time automatically and is not interrupted if you click something else on the window. There are some comments around the code to help you understand what's happening.
import java.awt.*;
import javax.swing.*;
import java.util.*;
class Clock extends JFrame implements Runnable
{
Thread runner; //declare global objects
Font clockFont;
public Clock()
{
super("Java clock");
setSize( 350, 100);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setVisible(true);
setResizable(false); //create window
clockFont = new Font("Serif", Font.BOLD, 40); //create font instance
Container contentArea = getContentPane();
ClockPanel timeDisplay = new ClockPanel();
contentArea.add(timeDisplay); //add components
setContentPane(contentArea);
start(); //start thread running
}
class ClockPanel extends JPanel
{
public void paintComponent(Graphics painter )
{
Image pic =
Toolkit.getDefaultToolkit().getImage("background.jpg");
if(pic != null)
painter.drawImage(pic, 0, 0, this); //create image
//if I didn't use a background image I would have used the setColor and fillRect methods to set background
painter.setFont(clockFont); //create clock components
painter.setColor(Color.black);
painter.drawString( timeNow(), 60, 40);
}
}
//get current time
public String timeNow()
{
Calendar now = Calendar.getInstance();
int hrs = now.get(Calendar.HOUR_OF_DAY);
int min = now.get(Calendar.MINUTE);
int sec = now.get(Calendar.SECOND);
String time = zero(hrs)+":"+zero(min)+":"+zero(sec);
return time;
}
public String zero(int num)
{
String number=( num < 10) ? ("0"+num) : (""+num);
return number; //Add leading zero if needed
}
public void start()
{
if(runner == null) runner = new Thread(this);
runner.start(); //method to start thread
}
public void run()
{
while (runner == Thread.currentThread() )
{
repaint();
//define thread task
try
{
Thread.sleep(1000);
}
catch(InterruptedException e)
{
System.out.println("Thread failed");
}
}
}
//create main method
public static void main(String [] args)
{
Clock eg = new Clock();
}
}
import java.awt.*;
import javax.swing.*;
import java.util.*;
class Clock extends JFrame implements Runnable
{
Thread runner; //declare global objects
Font clockFont;
public Clock()
{
super("Java clock");
setSize( 350, 100);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setVisible(true);
setResizable(false); //create window
clockFont = new Font("Serif", Font.BOLD, 40); //create font instance
Container contentArea = getContentPane();
ClockPanel timeDisplay = new ClockPanel();
contentArea.add(timeDisplay); //add components
setContentPane(contentArea);
start(); //start thread running
}
class ClockPanel extends JPanel
{
public void paintComponent(Graphics painter )
{
Image pic =
Toolkit.getDefaultToolkit().getImage("background.jpg");
if(pic != null)
painter.drawImage(pic, 0, 0, this); //create image
//if I didn't use a background image I would have used the setColor and fillRect methods to set background
painter.setFont(clockFont); //create clock components
painter.setColor(Color.black);
painter.drawString( timeNow(), 60, 40);
}
}
//get current time
public String timeNow()
{
Calendar now = Calendar.getInstance();
int hrs = now.get(Calendar.HOUR_OF_DAY);
int min = now.get(Calendar.MINUTE);
int sec = now.get(Calendar.SECOND);
String time = zero(hrs)+":"+zero(min)+":"+zero(sec);
return time;
}
public String zero(int num)
{
String number=( num < 10) ? ("0"+num) : (""+num);
return number; //Add leading zero if needed
}
public void start()
{
if(runner == null) runner = new Thread(this);
runner.start(); //method to start thread
}
public void run()
{
while (runner == Thread.currentThread() )
{
repaint();
//define thread task
try
{
Thread.sleep(1000);
}
catch(InterruptedException e)
{
System.out.println("Thread failed");
}
}
}
//create main method
public static void main(String [] args)
{
Clock eg = new Clock();
}
}
