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javaswingjbuttonpaintcomponent

Jbutton that draws on a new Jpanel


i'd like this button to (on click) draw an Oval. Problem is that eclipse says something about missing semicolons (in the action listener definition) and i dont understand why. Whats the proper way of passing methods (bulid in or custom) to the action listeners?

public class figury implements ActionListener {

    public figury() {

        frame();
    }

    public void frame() {

        JFrame f = new JFrame();
        f.setVisible(true);
        f.setSize(480, 480);
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        JPanel p = new JPanel();
        JButton kolo = new JButton("Rysuj kolo");


        JButton kolo = new JButton("Rysuj kwadrat");
        kwadrat.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                public void paintComponent(Graphics g){
                    g.fillOval(50,50,100,100);
                    g.setColor(Color.RED);
                }
            }
        });

        p.add(kolo);
        f.add(p);
    }

    public static void main(String[] args) {

        new figury();

    }
}

Solution

  • You are trying to define a method inside another method there. In your case, the problem is in the line containing

    public void paintComponent(Graphics g) {
    ...
    

    This cannot be defined inside another method in java. There are good ideas for painting in java in these official documentation links and stackoverflow questions:

    How to make canvas with Swing?

    http://www.oracle.com/technetwork/java/painting-140037.html