code: import java.awt.event.*;
  import javax.swing.*;
  
  public class Test extends JFrame {
  
      Test() {
          addKeyListener(new KeyAdapter() {
              @Override
              public void keyPressed(KeyEvent e) {
                  int keyCode = e.getKeyCode();
                  System.out.println(keyCode);
              }
          });
      }
  
      public static void main(String[] args) {
          SwingUtilities.invokeLater(() -> {
              Test f = new Test();
              f.setFocusable(true);
              f.setVisible(true);
          });
      }
  }
  