键绑定不起作用，Java SE，Swing

Question

I'm trying to add a shortcut to my JButton. I've read How to Use Key Bindings tutorial and I also have read this page How to use Key Bindings instead of Key Listeners and a loooooooooooooot of other questions about key bindings, but haven't found any answer for me

What I've tried:

public class Example extends JFrame {

    public static void main(String args[]) {
        Example example = new Example();
    }

    Example(){
        Action action = new Action() {
            @Override
            public Object getValue(String key) {
                return null;
            }

            @Override
            public void putValue(String key, Object value) {

            }

            @Override
            public void setEnabled(boolean b) {

            }

            @Override
            public boolean isEnabled() {
                return false;
            }

            @Override
            public void addPropertyChangeListener(PropertyChangeListener listener) {

            }

            @Override
            public void removePropertyChangeListener(PropertyChangeListener listener) {

            }

            @Override
            public void actionPerformed(ActionEvent e) {
                System.out.println("Hello World!");
            }
        };

        JButton button = new JButton("Hello World!");
        button.getInputMap(JComponent.WHEN_IN_FOCUSED_WINDOW).put(KeyStroke.getKeyStroke("RIGHT"), "doSomething");
        button.getActionMap().put("doSomething", action);
        button.addActionListener(action);

        add(button);
        setVisible(true);
        pack();
    }

}

I've also tried to make it like that: getInputMap(JComponent.WHEN_IN_FOCUSED_WINDOW).put(KeyStroke.getKeyStroke(KeyEvent.VK_RIGHT, 0, true), "doSmth");

But nothing seems to be working, what am I doing wrong?

Answer 1

Your Action has a method called isEnabled that you've implemented. The Javadoc on it states:

/**
 * Returns the enabled state of the <code>Action</code>. When enabled,
 * any component associated with this object is active and
 * able to fire this object's <code>actionPerformed</code> method.
 *
 * @return true if this <code>Action</code> is enabled
 */

Since you return a hardcoded false , the Action is never enabled and the actionPerformed method is never called. Your problem is not the binding, it's the action itself!

A simple fix is to change isEnabled to return true, or, even simpler yet, use AbstractAction in place of Action , and override only actionPerformed ( AbstractAction is kind of the "I don't care about all this stuff, just give me the simplest thing possible with one method to implement!")