Pourquoi mon carré ne se déplace pas ?

import javax.swing.*;
import java.awt.*;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;

public class Main extends JPanel implements KeyListener {
 
 int i = 10;
 int j = 10;
 
 public void display() {
  JFrame fen = new JFrame();
  fen.setVisible(true);
  fen.setSize(480, 272);
  fen.setTitle("Ma fenêtre intelligente !");
  fen.add(this);
  fen.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
  this.setBackground(Color.YELLOW);
 }
 
 public void paintComponent(Graphics g) {
  g.setColor(Color.BLUE);
  g.fillRect(i, j, 100, 100);
 }

 public static void main(String[] args) {
  // TODO Auto-generated method stub
  System.out.println("Coucou");
  Main classe = new Main();
  classe.display();
 }

 @Override
 public void keyPressed(KeyEvent arg0) {
  // TODO Auto-generated method stub
  if(arg0.getKeyCode() == KeyEvent.VK_A) {
   i += 10;
   repaint();
  }
  
 }

 @Override
 public void keyReleased(KeyEvent arg0) {
  // TODO Auto-generated method stub
  
 }

 @Override
 public void keyTyped(KeyEvent arg0) {
  // TODO Auto-generated method stub
  
 }

}