Time elapsed on canvas java

Question

so I am trying to add a Jlabel to show the time elpased on my program but i dont know where to put it and how to add one. I tried using one of the codes that I found and my program just hanged. Hope you can help me:

here's a gist of my code, I have 2 separate java file for my GUI

public class MyFrame extends JFrame implements Serializable,ActionListener{ 
    Canvas canvas;
    CanvasManager manager;

    public MyFrame() {
        canvas = new Canvas();
        canvas.setSize(600,700);
        this.add(canvas);
        canvas.setBackground(Color.green);

        this.pack();
        this.setVisible(true);
        this.setResizable(false);
        this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        manager = new CanvasManager(canvas);
        manager.start();
  }

this is my canvas where i draw my images:

public class CanvasManager extends Thread implements MouseListener, Serializable{
    private final int FRAME_DELAY = 200; // 20ms. implies 50fps (1000/20) = 50

    private BufferedImage img;
    private boolean toggle = true;
    private int width = 600;
    private int height = 700;

    private Canvas canvas;
    private long start;

    public CanvasManager(Canvas canvas) {
       this.canvas = canvas;
       this.canvas.setSize(width, height);
       this.canvas.addMouseListener(this);
    }

    public void run() {
       start = System.currentTimeMillis();
       canvas.createBufferStrategy(2);
       BufferStrategy strategy = canvas.getBufferStrategy();
       Graphics g = null;
       while (true) {
          g = strategy.getDrawGraphics();
          paint(g);
          strategy.show();
          syncFramerate();
       }
    }

I have a thread for my paint function because my program requires to keep repainting the canvas.

Answer 1

A solution would be to add a Jlabel to the class that extends frame.

JLabel lbl = new JLabel("Text"); // instance variable
this.add(lbl); // this should go in constructor

Then as time passes, you would update the text in the JLabel

lbl.setText("Time");

Then in your game loop you would initiate a Timer/ Swing Timer and change the Text of the JLabel when the time action is fired...

Timer timer = new Timer(1000, new ActionListener() { //Change parameters to your needs.
            @Override
            public void actionPerformed(ActionEvent e) {
               //setText of JLabel here every second/
            }
        });

Then call

timer.start();

when you want to start calculating the elapsed time which I would assume you want it at the start of the program.. So I would just call this method in the gameLoop, if the Timer hasn't already been started.

Heres the API:

https://docs.oracle.com/javase/7/docs/api/javax/swing/Timer.html