call paintcomponent for a jpanel in jframe

问题

I have a JFrame with a JPanel on it (JPanel is private in JFrame). Now I want to override JPanel by using paintComponent method.

How can I do that?

回答1:

When you create your instance of JPanel, (assuming you're doing it this way), do this:

JPanel panel = new JPanel(){
    @Override
    public void paintComponent(Graphics g){
       // paint code
    }
};

The other alternative is to create a private class which extends JPanel.
For example:

public class OuterClass{
    // fields, constructors, methods etc..

    private class MyPanel extends JPanel{   
       // fields, constructors, methods etc..

       @Override
       public void paintComponent(Graphics g){
          // paint code
       }

    }
}

回答2:

not clear from your question, but I think that nothing complicated override paintComponent for Swing JComponents, please avoid to use method paint() for Swing JComponents, use only paintComponent()

来源：https://stackoverflow.com/questions/9219762/call-paintcomponent-for-a-jpanel-in-jframe