Make JSpinner Select Text When Focused

Question

I would like to change the behavior of a JSpinner so that when you click on the text, it selects it. This makes it easier to replace the field with the value that you want.

Answer 1

Much of the problem you are facing has to do with how the spinner validates any values within the spinner AFTER a focus event (and several other state events), which will circumvent the highlight.

The MacOS is even worse.

What I ended up doing was starting a Thread that waited a very short time period (around 25 milliseconds) and then used SwingUtilities.invokeLater to actually perform the selection...

Updated with a example

import java.awt.Component;
import java.awt.EventQueue;
import java.awt.GridBagLayout;
import java.awt.event.FocusAdapter;
import java.awt.event.FocusEvent;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import javax.swing.JButton;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JSpinner;
import javax.swing.SpinnerNumberModel;
import javax.swing.SwingUtilities;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
import javax.swing.text.JTextComponent;

public class AutoFocusSpinner {

    public static void main(String[] args) {
        new AutoFocusSpinner();
    }

    public static final SelectOnFocusGainedHandler SHARED_INSTANCE = new SelectOnFocusGainedHandler();

    public AutoFocusSpinner() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (ClassNotFoundException ex) {
                } catch (InstantiationException ex) {
                } catch (IllegalAccessException ex) {
                } catch (UnsupportedLookAndFeelException ex) {
                }

                JSpinner spinner = new JSpinner(new SpinnerNumberModel(1, 0, 100, 1));
                installFocusListener(spinner);

                JFrame frame = new JFrame("Test");
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.setLayout(new GridBagLayout());
                frame.add(spinner);
                frame.add(new JButton("Here for testing"));
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }

        });
    }

    public void installFocusListener(JSpinner spinner) {

        JComponent spinnerEditor = spinner.getEditor();

        if (spinnerEditor != null) {

            // This is me spending a few days trying to make this work and 
            // eventually throwing a hissy fit and just grabbing all the 
            // JTextComponent components contained within the editor....
            List lstChildren = findAllChildren(spinner, JTextComponent.class);
            if (lstChildren != null && lstChildren.size() > 0) {

                JTextComponent editor = lstChildren.get(0);
                editor.addFocusListener(SHARED_INSTANCE);

            }

        }

    }

    public static  List findAllChildren(JComponent component, Class clazz) {

        List lstChildren = new ArrayList(5);
        for (Component comp : component.getComponents()) {

            if (clazz.isInstance(comp)) {

                lstChildren.add((T) comp);

            } else if (comp instanceof JComponent) {

                lstChildren.addAll(findAllChildren((JComponent) comp, clazz));

            }

        }

        return Collections.unmodifiableList(lstChildren);

    }

    public static class SelectOnFocusGainedHandler extends FocusAdapter {

        @Override
        public void focusGained(FocusEvent e) {

            Component comp = e.getComponent();
            if (comp instanceof JTextComponent) {
                final JTextComponent textComponent = (JTextComponent) comp;
                new Thread(new Runnable() {
                    @Override
                    public void run() {
                        try {
                            Thread.sleep(25);
                        } catch (InterruptedException ex) {
                        }
                        SwingUtilities.invokeLater(new Runnable() {
                            @Override
                            public void run() {
                                textComponent.selectAll();
                            }
                        });
                    }
                }).start();
            }            
        }        
    }
}

Now, right about now, I'm praying for some really nice, simple, undocumented property that we can set that will mean we don't need to do all this :P