我创建了一个JFrame。当我使用Graphics2D.drawline（）在x轴和y轴上绘制一条起点为x=0，y=0的线时，它并不是从JFrame的x=0轴开始的。我该怎么办？enter image description here

import java.awt.BasicStroke;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import javax.swing.JFrame;

public class MyGraphics extends JFrame{

MyGraphics(){

    this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    this.setSize(500,500);
    this.setVisible(true);

}
public void paint(Graphics g){

    Graphics2D g2D = (Graphics2D)g;

    g2D.setPaint(Color.blue);
    g2D.drawLine(0, 0, 500, 500);
    g2D.setStroke(new BasicStroke(5));
}
}