Displaying background image with java nullpointerexception

Question

My goal right now is to set a background image with "black.png".

package testing;
import javax.swing.*;
import java.awt.*;
public class test extends Panel {
    test Panel;
    Image background;

    //image loading
    public void paint(Graphics bg) {
        bg.drawImage(background, 20, 20, null);
    }

    public static void main (String[] args) {
        Image background = Toolkit.getDefaultToolkit().createImage("black.png");
        test panel = new test();
        panel.paint(null);
    }
}

and the output :

Exception in thread "main" java.lang.NullPointerException
at testing.test.paint(test.java:10)
at testing.test.main(test.java:16)

Why doesn't line 10 and 16 point to null? And is it possible to just display a black background then overlay images that I want to?

Possible duplicate of [What is a NullPointerException, and how do I fix it?](https://stackoverflow.com/questions/218384/what-is-a-nullpointerexception-and-how-do-i-fix-it) — , Aug 09 '18 at 13:52
@raul1ro i did but it says file cannot be resolved to a type — xxboomxx, Aug 09 '18 at 13:57
Possible duplicate of [java pick random images](https://stackoverflow.com/questions/21025595/java-pick-random-images) — Nicholas K, Aug 10 '18 at 17:44

score 0 · Answer 1 · answered Aug 09 '18 at 13:50

0

You are explicitly passing null into your paint() method on line 16.

answered Aug 09 '18 at 13:50

Kevin Swan

147
12

so what should i do? – xxboomxx Aug 09 '18 at 13:59
@xxboomxx pass initialized `Graphics` instance instead. `Graphics gr = panel.getGraphics();` for example – Nikolai Shevchenko Aug 09 '18 at 14:15

Displaying background image with java nullpointerexception

1 Answers1