Java Swing How to - Use KeyListener with JFrame

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Question

We would like to know how to use KeyListener with JFrame.

Answer

import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
//from   www. ja  v a 2  s  .c o m
import javax.swing.JComponent;
import javax.swing.JFrame;

class mainDraw extends JComponent {

  public int x = 50;
  public int y = 50;

  public void paintComponent(Graphics g) {
    super.paintComponent(g);
    g.drawRect(x, y, 50, 50);
    g.fillRect(x, y, 50, 50);
    g.setColor(Color.BLACK);
  }

  public void moveRight() {
    x = x + 5;
    repaint();
  }

  public void moveLeft() {
    x = x - 5;
    repaint();
  }

  public void moveDown() {
    y = y + 5;
    repaint();
  }

  public void moveUp() {
    y = y - 5;
    repaint();
  }
}

public class Main extends JFrame implements KeyListener {
  private mainDraw draw;

  public void keyPressed(KeyEvent e) {
    System.out.println("keyPressed");
  }

  public void keyReleased(KeyEvent e) {
    if (e.getKeyCode() == KeyEvent.VK_RIGHT)
      draw.moveRight();
    else if (e.getKeyCode() == KeyEvent.VK_LEFT)
      draw.moveLeft();
    else if (e.getKeyCode() == KeyEvent.VK_DOWN)
      draw.moveDown();
    else if (e.getKeyCode() == KeyEvent.VK_UP)
      draw.moveUp();

  }

  public void keyTyped(KeyEvent e) {
    System.out.println("keyTyped");
  }

  public Main() {
    this.draw = new mainDraw();
    addKeyListener(this);
    setFocusable(true);
    setFocusTraversalKeysEnabled(false);
  }

  public static void main(String[] args) {
    Main frame = new Main();
    frame.setResizable(false);
    frame.setSize(600, 600);
    frame.setMinimumSize(new Dimension(600, 600));
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.getContentPane().add(frame.draw);
    frame.pack();
    frame.setVisible(true);
  }
}

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