Java by API/javax.swing/ActionMap

ActionMap: put(Object key, Action action)

import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.InputEvent;
import java.awt.event.KeyEvent;
import javax.swing.AbstractAction;
import javax.swing.Action;
import javax.swing.ActionMap;
import javax.swing.InputMap;
import javax.swing.JButton;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.KeyStroke;
public class MainClass {
  public static void main(String args[]) {
    String ACTION_KEY = "The Action";
    
    JFrame frame = new JFrame("KeyStroke Sample");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    JButton buttonA = new JButton("FOCUSED (control alt 7)");
    JButton buttonB = new JButton("FOCUS/RELEASE (VK_ENTER)");
    JButton buttonC = new JButton("ANCESTOR  (VK_F4+SHIFT_MASK)");
    JButton buttonD = new JButton("WINDOW (" ")");
    Action actionListener = new AbstractAction() {
      public void actionPerformed(ActionEvent actionEvent) {
        JButton source = (JButton) actionEvent.getSource();
        System.out.println("Activated: " + source.getText());
      }
    };
    KeyStroke controlAlt7 = KeyStroke.getKeyStroke("control alt 7");
    InputMap inputMap = buttonA.getInputMap();
    inputMap.put(controlAlt7, ACTION_KEY);
    ActionMap actionMap = buttonA.getActionMap();
    actionMap.put(ACTION_KEY, actionListener);
    KeyStroke enter = KeyStroke.getKeyStroke(KeyEvent.VK_ENTER, 0, true);
    inputMap = buttonB.getInputMap();
    inputMap.put(enter, ACTION_KEY);
    buttonB.setActionMap(actionMap);
    KeyStroke shiftF4 = KeyStroke.getKeyStroke(KeyEvent.VK_F4,
        InputEvent.SHIFT_MASK);
    inputMap = buttonC
        .getInputMap(JComponent.WHEN_ANCESTOR_OF_FOCUSED_COMPONENT);
    inputMap.put(shiftF4, ACTION_KEY);
    buttonC.setActionMap(actionMap);
    KeyStroke space = KeyStroke.getKeyStroke(" ");
    inputMap = buttonD.getInputMap(JComponent.WHEN_IN_FOCUSED_WINDOW);
    inputMap.put(space, ACTION_KEY);
    buttonD.setActionMap(actionMap);
    frame.setLayout(new GridLayout(2, 2));
    frame.add(buttonA);
    frame.add(buttonB);
    frame.add(buttonC);
    frame.add(buttonD);
    frame.setSize(400, 200);
    frame.setVisible(true);
  }
}