Error: cannot find symbol super.paintComponent(g) in Java

Question

I seem to get the error:

error: cannot find symbol
        super.paintComponent(g);
             ^
  symbol: method paintComponent(Graphics)

very often in my code. I always seem to fix it, but this is always after as much as an hour of hair pulling trying to find the solution on a coding thread from 5 years ago. Also, I never seem to remember what I did. So, I am finally asking the graphics pros here. I wrote a little test program that should display a coordinate plane on the JFrame, but instead, I receive this error. I am fairly new to graphics in java, so I have not tried much, except calling repaint on all sorts of components. This is my code:

import javax.swing.*;
import java.awt.*;

public class Graph extends JFrame {
        public void showFrame(){
                setSize(400, 400);
                setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

                JPanel plane = new JPanel();
                add(plane);

                setVisible(true);
                repaint();
        }

        public static void main(String[] args){
                Graph graph = new Graph();
                graph.showFrame();
        }

        public void paintComponent(Graphics g){
                super.paintComponent(g);
                g.setColor(Color.black);
                g.drawLine(200, 0, 200, 400);
                g.drawLine(0, 200, 400, 200);
        }
}

Any help is appreciated. Thank you in advance.

Answer 1

JFrame doesn't have this method. It has

 public void paintComponents(Graphics g)

inherited from java.awt.Container.