import javax.swing.*; import java.awt.*; public class Game extends JFrame{ public Game(){ setResizable(false); setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE); setSize(300, 300); setLocationRelativeTo(null); setVisible(true); } public void paint(Graphics g){ g.setColor(Color.BLACK); g.fillOval(100, 100, 100, 100); } public static void main(String[] args) { Game game = new Game(); game.paint(null); } }
  • 3
    Well, you yourself pass null . - Alexander Petrov
  • 3
    game.paint (null); - tCode
  • I just can not figure out how to do differently. Graphics is an abstract class and does not create instances ... And if you try to create a descendant of a class, you need to override a bunch of methods ... - Wuzaza

2 answers 2

Regarding the NPE exception, you can and should read here: What is a Null Pointer Exception and how to fix it?

It makes no sense to copy such a large text.

awt can say the following about awt and the paint method: the awt engine calls the paint method every time the operating system reports that something needs to be painted on the canvas. It is called when a window is first created, or when we minimize / maximize a window, resize it with a mouse, etc. Such messages are sent constantly, implicitly, by the virtual machine. And, as a result, there is no need to call it.

Those. in your case, just write

 public static void main(String[] args) { Game game = new Game(); }

A window will be created and paint will automatically pick up.

    You just do not need to call paint (), it is called implicitly by the virtual machine.

    • Thank you very much! - Wuzaza