Java: how do I remove the default keystrokes from any JComponent?

I want to control which keystrokes belong to which JComponent I even want to know how to delete the default keystroke associated with JComponent and replace it with other favorite keystrokes

I followed the Oracle tutorial, which gave an example of JButton. I tried it and it worked normally, but it didn't work when I tried it with jcombobox!

I tried to delete the space key to prevent JComponent from responding to the space key

I deleted the space key with this Code:

firstButton.getInputMap().put(Keystroke.getKeystroke("SPACE"),"none");

JCombo@R_850_2419 @The same is true

sizesCombo@R_850_2419@.getInputMap().put(Keystroke.getKeystroke("SPACE"),"none");

But it doesn't work, it（ JCombo@R_850_2419 @) still respond to the space key

For the firstbutton I deleted the space printer effect; I added the F key, so now when you press the F key on the keyboard, you press the first button, and ant doesn't respond to space Note that even if the firstbutton has no focus, f will be pressed (JComponent. When_in_focused_window)

This is an sscce code showing my example: Note: I deliberately did not add the above code line to the second button "secondbutton", so it still responds to space by default

import java.awt.BorderLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ItemEvent;
import java.awt.event.ItemListener;
import javax.swing.*;

public class KeystrokeTest extends JPanel
{

    JPanel widgetPanel;
    JPanel textAreaPanel;
    JButton firstButton;
    JButton secondButton;
    JTextArea textArea;
    JCombo@R_850_2419@<Integer> sizesCombo@R_850_2419@;

    public Keystroketest()
    {
        firstButton = new JButton("First");
        firstButton.addActionListener(eventWatcher);
        firstButton.getInputMap().put(Keystroke.getKeystroke("SPACE"),"none");
        firstButton.getInputMap(JComponent.WHEN_IN_FOCUSED_WINDOW).put(Keystroke.getKeystroke("F"),"F Key");
        firstButton.getActionMap().put("F Key",eventWatcher);

        secondButton = new JButton("Second");
        secondButton.addActionListener(eventWatcher);

        sizesCombo@R_850_2419@ = new JCombo@R_850_2419@<>();
        sizesCombo@R_850_2419@.addItemListener(new itemListenerClass());
        for (int i = 1; i <= 8; i++)
        {
            sizesCombo@R_850_2419@.addItem(i);
        }
        sizesCombo@R_850_2419@.setSelectedIndex(0);
        sizesCombo@R_850_2419@.getInputMap().put(Keystroke.getKeystroke("SPACE"),"none");


        textArea = new JTextArea(0,0);
        JScrollPane scrollTextArea = new JScrollPane(textArea);
        scrollTextArea.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_ALWAYS);
        textArea.setEditable(false);

        widgetPanel = new JPanel();
        textAreaPanel = new JPanel(new BorderLayout());

        widgetPanel.add(firstButton);
        widgetPanel.add(secondButton);
        widgetPanel.add(sizesCombo@R_850_2419@);

        textAreaPanel.add(scrollTextArea,BorderLayout.CENTER);

        JSplitPane splitPane = new JSplitPane(JSplitPane.HORIZONTAL_SPLIT,textAreaPanel,widgetPanel);
        splitPane.setDividerLocation(280);
        splitPane.setResizeWeight(.5d);
        this.setLayout(new BorderLayout());
        this.add(splitPane);
    }
    AbstractAction eventWatcher = new AbstractAction()
    {
        @Override
        public void actionPerformed(ActionEvent ae)
        {
            Object source = ae.getSource();
            if (source == firstButton)
            {
                textArea.append("First button clicked\n");
            }
            if (source == secondButton)
            {
                textArea.append("Second button clicked\n");
            }
        }
    };

    private class itemListenerClass implements ItemListener
    {

        @Override
        public void itemStateChanged(ItemEvent e)
        {
            if (e.getSource() == sizesCombo@R_850_2419@)
            {
                if (textArea != null)
                {
                    textArea.append("Item " + sizesCombo@R_850_2419@.getSelectedItem() + "\n");
                }
            }
        }
    }

    private static void createAndShowGUI()
    {
        JFrame frame = new JFrame("Keystroke Test");
        frame.setDefaultCloSEOperation(JFrame.EXIT_ON_CLOSE);
        frame.setSize(500,300);
        frame.add(new Keystroketest(),BorderLayout.CENTER);
        frame.setVisible(true);
    }

    public static void main(String[] args)
    {
        SwingUtilities.invokelater(new Runnable()
        {
            public void run()
            {
                UIManager.put("swing.boldMetal",Boolean.FALSE);
                createAndShowGUI();
            }
        });
    }
}

The reason why I want to control the default keystroke of JComponent is because I want to delete the default effect of space on all jcomponents. Except for a button, it will respond to space press. No matter where the focus is, use JComponent WHEN_ IN_ FOCUSED_ Therefore, clicking another component (and moving the focus away from the exception button) will not prevent space from affecting the button

Another point: if you test the above code, you will notice that from JCombo@R_850_2419 @Selecting an item in will produce two rows. If you select item "4", the output in jtextarea is

Why two?

thank you.

Solution

You should use JComponent. Like this WHEN_ ANCESTOR_ OF_ FOCUSED_ Component inputmap (you may notice that I used keyevent and keystroke.getkeystroke (int key, int modifier, Boolean onrelease) because it is easier to read and less prone to errors, that is, typing wrong string parameters, etc.):

sizesCombo@R_850_2419@.getInputMap(JComponent.WHEN_ANCESTOR_OF_FOCUSED_COMPONENT)
        .put(Keystroke.getKeystroke(KeyEvent.VK_SPACE,false),"none");

As far as I know, the reason well explains here:

So I infer JCombo@R_850_2419 @Is a composite component, so we need the correct inputmap – when_ ANCESTOR_ OF_ FOCUSED_ Component to delete the keybinding function of all internal components of its specific key, i.e. space

As @ mkorbel said (one of his comments) two things may happen:

>Deselect an item > selected an item

These events appear in pairs, just as we deselect the old value when we select a new value Therefore, we must examine and take appropriate action:

@Override
public void itemStateChanged(ItemEvent e)
{
   if(e.getStateChange()==ItemEvent.SELECTED) { 
       //am item was selected do something
   }
}

Other recommendations:

>Do not call SetSize. > on JFrame Use appropriate LayoutManager and / or override getPreferredSize to return Dimensions that is suitable for content, and call pack () on JFrame after setting up visibility and adding components.