Repainting JPanel

[Bhakta Pradhan]

Hi,
I just started learning Swing.I'm trying to write a program in which there will be 2 panels.Panel1->for stopwatch Panel2->which will be displaying some data and it contains a button.

My concern is I'm using Threading to update the timer of stopwatch every second. After putting print statement i can see the stop watch part is running fine but the stopwatch panel is not getting updated every second.

Below is the some portion of my code relevant to this problem.

Can anybody help me out plzzzzzzzz!!!

public class GUIPanel extends JFrame{
	GUIPanel(){		
		this.setLayout(new GridLayout(3,1));
		PanelTop block = new PanelTop();
		Panel1 block1=new Panel1();
		PanelBottom block2=new PanelBottom();
		this.add(block);
		this.add(block1);
		this.add(block2);
		this.setSize(200,200);
	    this.setVisible(true);
	    
	    /*
	     * Call to repaint thread
	     */
	    Thread timerPanel=new Thread(block);
		timerPanel.start();
	    
	}
	
	public static void main(String[] args) {
		new GUIPanel();
		StopWatch stopWatch=new StopWatch();
		Thread timer=new Thread(stopWatch);
		timer.start();
	}
	
}

PanelTop is the Class for stopwatch panel

public class PanelTop extends JPanel implements Runnable{
	private JLabel jblMsg;
	private JLabel jblTime;
	private long timeElapsed;
	private String timer;
	
	PanelTop(){
		this.setLayout(new GridLayout(1, 2));
		jblMsg=new JLabel("Game Begins",0);
		timeElapsed=StopWatch.getElapsedTime();
		timer=Long.toString(timeElapsed);
		jblTime=new JLabel(timer,0);
		jblMsg.setOpaque(true);
		jblMsg.setBackground(Color.cyan);
		jblTime.setOpaque(true);
		jblTime.setBackground(Color.cyan);
		this.add(jblMsg);
		this.add(jblTime);
		this.setVisible(true);
		}

	public void run() {
		while(true){
		timeElapsed=StopWatch.getElapsedTime();
		timer=Long.toString(timeElapsed);
		System.out.println("running::::"+timer);
		revalidate();
		repaint();
		setVisible(true);
		}
	}
}

Please let me know if my approach should be something else so as to achieve the requirement
Thanks in advance

[Campbell Ritchie]

You are using one thread to start the StopWatch, and you are querying it in another thread. It is worthwhile checking the interval between successive queries, because I think those intervals are too short for repainting.

If you have just started learning Swing, you might do well to try simpler examples. And remember that Swing components are not thread-safe.

[Bhakta Pradhan]

Hi All,

I solved this , actually I was not updating the timer label inside run method of PanelTop.java

this.jblTime.setText(timer);

Hi Campbell,

Thanks for spending some time to look into this problem.

Actually the Stopwatch code goes below ,I don't think it could be a problem in this scenario. What you say???

public class StopWatch implements Runnable{
    
    private static long startTime = 0;
    private static long stopTime = 0;
    private static long elapsedTime = 0;
    private static boolean running = false;
    
    public void run() {
    	StopWatch.startTimer();
    	while(true){
    		
			StopWatch.elapsedTime=StopWatch.calculateElapsedTimeSecs();
			System.out.println(elapsedTime);
		}
		
	}
    
    public static void startTimer() {
        startTime = System.currentTimeMillis();
        running = true;
    }
    
    
    //elaspsed time in seconds
    public static long calculateElapsedTimeSecs() {
        long elapsed;
        if (running) {
            elapsed = ((System.currentTimeMillis() - startTime) / 1000);
        }
        else {
            elapsed = ((stopTime - startTime) / 1000);
        }
        return elapsed;
    }

	public static long getElapsedTime() {
		return elapsedTime;
	}
}

[Darryl Burke]

You need to respect Swing's single threaded rule.
http://java.sun.com/products/jfc/tsc/articles/threads/threads1.html
http://java.sun.com/products/jfc/tsc/articles/threads/threads3.html
http://download.oracle.com/javase/tutorial/uiswing/concurrency/index.html

[Rob Spoor]

I suggest you take a look at javax.swing.Timer (for use within GUIs) and java.util.Timer (for anywhere else).