Timer cannot stop (maybe the GUI error)

Question

I'm trying to create animation for a traffic light simulation that uses a timer. There is a button to stop the simulation, but clicking it does not seem to affect the animation. I did check in the animation but the animation seem like different places. Please help.

In the main class:

DataModels dm = new DataModels();
Simulation sm = new Simulation(dm);
sm.go();

Here is the simulation class:

public class Simulation extends JPanel implements ActionListener {
    DataModels dm;
    Timer tm = new Timer(20, this);
    private boolean ss = false;

    public Simulation(DataModels dm) {
        this.dm = dm;
        // redLightTime= dm.getRedLight()*1000;
    }

    public void go() {
        sm = new Simulation(dm);
        simulation = new JFrame();
        simulation.setTitle("Traffic light and Car park Siumulation");
        simulation.setSize(800, 700);
        simulation.setResizable(false);
        simulation.setVisible(true);
        simulation.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        simulation.add(sm, BorderLayout.CENTER);

        // Command button panel
        JPanel command = new JPanel();
        command.setPreferredSize(new Dimension(800, 100));
        // Pause or play button
        JButton pauseplayB = new JButton("Pause");
        pauseplayB.setSize(new Dimension(50, 50));
        pauseplayB.addActionListener(new ActionListener() {

            public void actionPerformed(ActionEvent e) {
                // Execute when button is pressed
                ss = true;
                System.out.println("You clicked the button");
            }
        });
        command.add(pauseplayB);
        JButton stopB = new JButton("Stop");
        JButton saveB = new JButton("Save");

        command.setLayout(new GridLayout(1, 1));
        command.add(stopB);
        command.add(saveB);
        simulation.add(command, BorderLayout.SOUTH);
    }

Now paintComponent will change based on timer change. The following code is also in the Simulation class.

public void paintComponent(Graphics g) {
    // Many other actions
    // ....
    startAnimation();
}

public void startAnimation() {
    if ( !false) {
        tm.start();
    } else {
        tm.stop();
    }
    // Checking button click
    System.out.println(ss);
}

According to the console output, the ss value never changes.

Is the JPanel being painted after you click the button? Why don't you try forcing your JPanel to repaint or invalidate itself when you click the button? *Although, a button click should invalidate the JPanel* — Redandwhite, Aug 29 '12 at 19:42
Also, consider changing your `if` statement to something more, *modern:* `if (!ss) { ... }` — Redandwhite, Aug 29 '12 at 19:44
Painted?? In the console line: got the check: You clicked the button but the value ss not change — Cao Linh Truong, Aug 29 '12 at 19:46
Does `System.out.println("You clicked the button");` get printed? (It's in your action listener.) — Roddy of the Frozen Peas, Aug 29 '12 at 19:48
I think this guy got same problem with me:http://stackoverflow.com/questions/8088002/how-to-use-a-swing-timer-to-start-stop-animation but which one was my answer — Cao Linh Truong, Aug 29 '12 at 20:02
to emphasize @JTMon 's answer: *never-ever* change the state of a component in its paintComponent. Also, I would suggest to change the name of the startAnimation, so it gets obvious that it is responsible for both starting and stopping. BTW: from your snippet, it's expected that ss always is the same, you never change it - could be that it's changed somewhere else - all the more reason to show an SSCCE instead of snippets :-) Unrelated: a) never-ever call setXXSize (instead, use a LayoutManager which suits your needs), b) remove pausePlayB.setSize, it has no effect anyway — kleopatra, Aug 30 '12 at 06:09

JTMon · Accepted Answer · 2012-08-30T08:04:38.563

4

The button's action listener should call the function to stop the timer somehow and not rely on the paint event to do it.

EDIT: Here is some code :)

public void actionPerformed(ActionEvent e) {
    // Execute when button is pressed
    ss = true;
    System.out.println("You clicked the button");
    startAnimation();
}

And the startAnimation method should have if(!ss) instead of if(!false)

edited Aug 30 '12 at 08:04

answered Aug 29 '12 at 19:44

JTMon

3,189
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An example would help round of te post ;) +1 none the less – MadProgrammer Aug 29 '12 at 20:32
@MadProgrammer You are definetly right but it was about 10 pm here when I posted :) – JTMon Aug 29 '12 at 20:36
Tks, please help i have stuck here for 2 days!! – Cao Linh Truong Aug 30 '12 at 04:22
as startAnimation actually is-meant-as toggleAnimation (or updateAnimationTimer), the action should probably toggle the flag `ss = !ss` (and the pause button's text updated appropriately) – kleopatra Aug 30 '12 at 09:10

score 3 · Answer 2 · answered Aug 29 '12 at 20:31

3

In addition to JTMon's suggestion, your startAnimation method contains a logic bomb

public void startAnimation() {
    if ( !false) { //<-- this will ALWAYS be true
        tm.start();
    } else {
        tm.stop();
    }
    // Checking button click
    System.out.println(ss);
}

The if statement that controls the timer will ALWAYS try & start the timer

answered Aug 29 '12 at 20:31

MadProgrammer

343,457
22
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That must be a typo in response to @RedAnwhite's comment as the original post had if(ss==false) :) – JTMon Aug 29 '12 at 20:38

Timer cannot stop (maybe the GUI error)

2 Answers2