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  1. #1
    wikemol is offline Member
    Join Date
    Jan 2012
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    Default Why won't this rectangle display in my JFrame?

    Why won't this rectangle appear on the content pane when I run the file?

    Main Class:

    package drawing;

    import javax.swing.JFrame;

    public class Main {

    public static void main(String[] args){
    JFrame frame = new JFrame();
    MyDrawPanel rect = new MyDrawPanel();


    frame.setSize(300, 300);



    MyDrawPanel class:

    package drawing;

    import java.awt.Color;
    import java.awt.Graphics;
    import javax.swing.JPanel;

    class MyDrawPanel extends JPanel{

    public void paintComponents(Graphics g){
    g.fillRect(20, 50, 100, 100);



  2. #2
    camickr is offline Senior Member
    Join Date
    Jul 2009
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    Default Re: Why won't this rectangle display in my JFrame?

    The method to override should be paintComponent() (without the "s").

    When overriding a method your code should be:

    Java Code:
    public void paintComponent(Graphics g)
    This way you will get a compile error if you have a typing mistake like this.

    Also, your code works because you are adding the panel to the center of the frame, but it will not work if you add it to the NORTH of the BorderLayout. When doing custom painting you need to:

    a) invoke super.paintComponent(...) at the start of the method
    b) override the getPreferredSize() method to return the preferred size of the panel so the layout manager can do its job.

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