从JFrame中的类绘制很多相同的对象

Question

Answer is written by me in the bottom of the question

I want to get a lot of 'Ates' objects in a frame. I tried a lot of examples but always failed.

In this context, I want to see a lot of rectangles which are going to left. However, there is just one and it is going faster and faster...

It does not show more than one object at the same time. Can you tell me what is the problem?

I used this code:

public class GamePanel extends JPanel
{
    public void paint(Graphics g)
    {
        super.paint(g);
        g.setColor(Color.BLACK);
        for(Ates a1 : StartGame.alist) // alist is an arraylist for Ates class objects
        {
            g.fillRect(a1.getX(), a1.getY(), 20, 20);
        }
        ...

Example creating:

public void sentAtes()
{
    r = rand.nextInt(471)+60;
    Ates a = new Ates(r);
    alist.add(a);
}

Ates class:

public Ates(int a)
{
    x = 700;
    y = a;
}

public int getX()
{
    return x;
}

public int getY()
{
    return y;
}

public void setX( int a )
{
    x = a;
}

public void setY( int a )
{
    y = a;
}

StartGame class:

public class StartGame extends JFrame implements KeyListener, ActionListener
{
    protected static ArrayList<Ates> alist = new ArrayList<Ates>();
    public static int cen = 0;
    ...
    public StartGame()
    {
        jp = new GamePanel();
        add(jp);
        ... 
        int delay = 10;
        ActionListener taskPerformed = new ActionListener()
        {
            @Override
            public void actionPerformed(ActionEvent e)
            {
                cen++;
                if(cen > 50)
                {
                    cen = 0;
                    sentAtes();
                }
                for(Ates a1 : alist)
                {
                    a1.setX(a1.getX()-1);
                }
                repaint();
            }
        };
        new Timer(delay,taskPerformed).start();
        ...

Info: If there is only one object, it is going left as expected.

Answer to my question.

In Ates class, you should not use static word for variables and use this. prefix to set them.

This should be work.

public class Ates extends JFrame
{

    protected int x;
    protected int y;

    public Ates(int a)
    {
        this.x = 700;
        this.y = a;
    }

Answer 1

Ok the only other thing I can see is that your StartGame() is only initialised once. Therefore your new Timer is only called once. Because it is the timer that is causing the ActionListener to be created it is only ever created and run through once and therefore can never reach the stage where it will create another rectangle. The actionPerformed() method only runs once in the program as there is no action or loop to cause it to run again.