摇摆动画开始停止

Question

this is my first post, so forgive me beginner´s mistakes.

the structure of my programme is the following:

I have a class that basicly creates an array of objects:

class fieldCreator extends JPanel
{
    ...
    fieldCell[] fieldArray;
    ...
    public fieldCreator()
    {
        while (counterVar < arraySize)
        {
            // fill the array randomly with one object out of three different classes
            if ((int)(Math.random()) == 0)
                this.fieldArray[counterVar] == new cellType0();
            ...
            counterVar++;
        }
    }
    public moveMethod()
    {
        // rearange the content of the array by a certain algorithm
        ...
        try 
        {
           Thread.sleep(150L); // this is to slow down the loop frequency
        }
        catch (Exception e) {}
    }
    public void paintComponent (Graphics g)
    {
        while (counterVar < arraySize)
        {
            // draw a rectangle for each object in the array in a specific color
            // create the illusion of a 2D field 
            counterVar++;
        }   
    }
}

The main class creates the framework end executes the methods:

class Main extends JPanel 
{
    ...
    public static fieldCreator myField;
    ...
    public static void main (String[] args)
    {

        main myMain = new main();
        myField = new fieldCreator();

        main.framework();

        // !!! this loop is what i want to start/stop by a button bash !!!
        while(true)
        {
            myField.moveMethod();
            myField.repaint();
        } 
    }  
    public void frameWork()
    {
        JFrame myFrame = new JFrame();
        JButton startButton = new JButton ("Start");
        JButton stopButton = new JButton ("Stop");
        startButton.addActionListener(new startListener());
        stopButton.addActionListener(new stopListener());
        myFrame.getContentPane().add(BorderLayout.NORTH, startButton);
        myFrame.getContentPane().add(BorderLayout.CENTER, myField);
        myFrame.getContentPane().add(BorderLayout.SOUTH, stopButton);
        ...
    }

    class startListener implements ActionListener
    {
        public void actionPerformed(ActionEvent e)
        {   
            //this does not work!!!
            //while(true)
            //{
            //    myField.moveMethod();
            //    myField.repaint();
            //}
        }
    }

    class stopListener implements ActionListener
    {
        public void actionPerformed(ActionEvent e)
        {
            // ---- this needs to be implemented ----
        }
    }
}

The programme works fine by starting and stopping it by the IDE, the field refreshes on every cycle and is displayed correctly. But when it comes to implementing the Buttons it does not refresh at all.

I hope the shortening of the code does not affect the understandability :) I appreciate every help!

Answer 1

The reason starting the animation from an ActionListener does not work, is that the loop blocks the event dispatch thread . The reason that the code appears to work when run from main() is that main() is run in another thread.

For a simple, timed repeating calls, like you have, the easiest is using a swing Timer .

As a side note, components should be also created in the EDT.

Answer 2

I solved the problem as follows:

class Main extends JPanel 
{
    public static void main(String[] args)
    {
        ...
        timer = new Timer(timerDelay, main.new timerListener());
        ...
    }

    class timerListener implements ActionListener
    {
        public void actionPerformed(ActionEvent e)
        {
            myField.moveMethod();
            myField.repaint();
        }
    }

    class startButtonListener implements ActionListener
    {
        public void actionPerformed(ActionEvent e)
        {
            timer.start();
            startButton.setText("RUNNING...");
        }
    }

    class stopButtonListener implements ActionListener
    {
        public void actionPerformed(ActionEvent e)
        {
            timer.stop();
            startButton.setText("START");
        }
    }
}