error: The local variable g may not have been initialized.

Hi,

I try to do drawOval in the JFrame as below (I want it as simple as possible). However, it not works. Can you tell me what I am missing?

import javax.swing.*;
import java.awt.*;
public class MyFrameClass {
public static void main(String[] args) {
JFrame frame = new JFrame();
frame.setSize(500,300);
frame.setVisible(true);
Graphics g;
g.drawOval(100,100,400,200); //error: The local variable g may not have been initialized.
}
}

 

try here--->http://www.java2s.com/Code/JavaAPI/java.awt/GraphicsdrawOvalintxintyintwidthintheight.htm