How To Write Key Listener

I want to make a program that will move a square to the left if you press "a", and to the right if you press "d". (Once I know how to do this I can figure out W and S for up and down by myself). What code would I use for doing that? Here is the program I have now. I used the oracle tutorial but it just shows how to handle for if ANY key is pressed.

This is what I used How to Write a Key Listener (The Java Tutorials > Creating a GUI With JFC/Swing > Writing Event Listeners)

Java Code:

import java.awt.BorderLayout;
import java.awt.Graphics;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JPanel;

public class myGame extends JComponent {
public int x = 20;
public int y = 20;

[code]....