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Thread: Painting Clock, Overlaps the current String display

  1. #1
    Java kindergarten chronoz13's Avatar
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    Default Painting Clock, Overlaps the current String display

    import java.awt.Color;
    import java.awt.Font;
    import java.awt.Graphics;
    import java.util.Calendar;
    import javax.swing.*;
     
    public class MyClock extends JPanel implements Runnable {
     
        Thread runner;
     
        public MyClock() {
     
            setDoubleBuffered(true);
            setFocusable(true);
            setLayout(null);
        }
     
        public void paintComponent(Graphics g) {
     
            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);
     
            g.drawString(time, 60, 40);
     
            repaint();
        }
     
        public String zero(int num) {
     
            String number = (num < 10) ? ("0" + num) : ("" + num);
            return number;                                   
        }
     
        public void start() {
     
            if (runner == null) {
     
                runner = new Thread(this);
            }
     
            runner.start();
        }
     
        public void run() {
     
            while (runner == Thread.currentThread()) {
     
                try {
     
                    Thread.sleep(1000);
                }
                catch (InterruptedException e) {
     
                    System.out.println("Thread failed");
                }
            }
        }
     
        public static void main(String[] args) {
     
            JFrame f = new JFrame();
            f.setSize(400, 300);
            f.add(new MyClock());
            f.setLocationRelativeTo(null);
            f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
            f.setVisible(true);
        }
    }

    i just gode this code from the web, with a little bit of modification, i need to implement a digital clock for another project.. i just cant figure out why does the next painting overlaps the current one.. any help please.


  2. #2
    Java kindergarten chronoz13's Avatar
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    Default Re: Painting Clock, Overlaps the current String display

    by the way.. my goal is.. to create a separate class as a Clock, but extends as a JPanel not a JFrame, i just want to add/call it to any JFrame window i have or in any JPanel/Container

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    Crazy Cat Lady KevinWorkman's Avatar
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    Default Re: Painting Clock, Overlaps the current String display

    1- Don't just throw code together you get from the internet. Take the time to really understand what's going on. You'll save yourself a ton of headaches. Recommended reading: Lesson: Performing Custom Painting (The Java™ Tutorials > Creating a GUI With JFC/Swing)

    2- Don't call repaint() from a paint method, including paintComponent(). Use a Swing Timer instead, otherwise you're going to be constantly drawing, which is really going to eat up a lot of resources.

    3- Your zero() method is doing the job of a DecimalFormat instance.

    4- JPanel's paintComponent() method redraws the background, which in effect clears out any previously drawn frames. Start your paintComponent() method with a call to super.paintComponent() in order to maintain that functionality.
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  4. The Following User Says Thank You to KevinWorkman For This Useful Post:

    chronoz13 (October 6th, 2011)

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