CODEWITHSUNDEEP
javaswingjpaneljlabelcountdown
Noah Cagle
Noah Cagle

Reputation: 146

Making an updating JLabel

I am new to programming (I'm 11 and hoping for java coding to be my career, but its just a hobby right now :)) and I just made a countdown program, here is the class:

package me.NoahCagle.JAVA;

import javax.swing.JFrame;

public class Main extends JFrame implements Runnable {
private static final long serialVersionUID = 1L;
public static int width = 600;
public static int height = 500;
public static String title = "Countdown!";
public static boolean running = false;
public int number = 11;
public Thread thread;
Dimension size = new Dimension(width, height);

public Main() {
    super(title);
    setSize(size);
    setResizable(false);
    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    setLocationRelativeTo(null);
    setVisible(true);
}

public static void main(String[] args) {
    Main m = new Main();
    m.start();
}

public void start() {
    if (running) {
        return;
    }

    running = true;
    Thread thread = new Thread(this);
    thread.start();

}

@SuppressWarnings("static-access")
public void run() {
    while (running) {
        number--;
        if (number == -1) {
            System.out.println("Done!");
            System.exit(0);
        }
        try {
        thread.sleep(1000);
        }catch (Exception e) {
            e.printStackTrace();
            System.exit(0);
        }
        System.out.println("" + number);
    }
}

public void stop() {
    if (!running) {
        return;
    }

    running = false;
    try {
        thread.join();
    }catch (Exception e) {
        e.printStackTrace();
        System.exit(0);
        }
    }
}

That may not have been necessary, but whatever. Well like I was saying, if you read the code, you will notice that it prints the value to the console. Well, if I could get that to display on a JLabel, while updating at the same time. I have tried just doing setText("" + number) thinking that because I have a thread going, it would repaint. But that didn't happen. It was just stuck at 11. Can someone please help me? Thanks

Upvotes: 2

Views: 162

Answers (2)

Sandiip Patil
Sandiip Patil

Reputation: 446

As 11yrs old you have done good job here. But where did you add any panel to the frame on which u want to show the number? Once you do it and put some label to add the number you will need to call the repaint method. Also to use threads with swings, there are many libraries you can use like Timer.

Happy Coding!

Upvotes: -1

MadProgrammer
MadProgrammer

Reputation: 347194

First, you may want to take a read through Concurrency in Swing. There are some very important constraints when it comes to dealing with multiple threads and Swing.

For your problem, you really should be using a javax.swing.Timer, and with examples...

Upvotes: 4

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