Java图形PaintComponent问题。 似乎找不到错误

Question

I'm making a program for drawing out an Image and it seems I've made a mistake and my program just doesn't want to draw out the image. Can someone please point out the mistake for mi because i really don't see it.

package basic_game_programing;

import java.awt.Graphics;
import java.awt.Image;


import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JPanel;

public class Practise extends JPanel {

public Image image;

        //#####PAINT__FUNCTION#####
        public void PaintComponent(Graphics g){
            super.paintComponent(g);

              ImageIcon character = new ImageIcon("C:/Documents and Settings/Josip/Desktop/game Šlije/CompletedBlueGuy.PNG");
              image = character.getImage();

              g.drawImage(image,20,20,null);
              g.fillRect(20, 20, 100, 100);
        }



//######MAIN__FUCTION#######
public static void main(String[]args){

    Practise panel = new Practise();


    //SETTING UP THE FRAME
    JFrame frame = new JFrame();
    //
    frame.setVisible(true);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setSize(500,500);
    frame.add(panel);


    //SETTING UP THE PANEL

    //









}

}

Answer 1

You're miscapitalizing paintComponent by using PaintComponent instead (note the first "P").

• So Change PaintComponent to paintComponent .
• Use the @Override annotation above the method to let the compiler tell you when you're making this kind of mistake.
• Never read an image into a painting method since this slows down a method that needs to be fast, and makes the image be read in over and over when one read is enough.
• The method should be protected not public .
• Use ImageIO.read(...) to read in your image, and use resources and relative path within the jar file, rather than use files or ImageIcons.
• Don't call setVisible(true) on the JFrame until after adding all components, else some might not show.
• Do read the tutorials as most all of this is well explained there.

eg,

public class Practise extends JPanel {

    private Image image;

    public Practice() {
        // read in your image here
        image = ImageIO.read(.......); // fill in the ...
    }

    @Override // use override to have the compiler warn you of mistakes
    protected void paintComponent(Graphics g){
        super.paintComponent(g);

        // never read within a painting method
        // ImageIcon character = new ImageIcon("C:/Documents and Settings/Josip/Desktop/game Šlije/CompletedBlueGuy.PNG");
        // image = character.getImage();

        g.drawImage(image, 20, 20, this);
        g.fillRect(20, 20, 100, 100);
    }
}