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. Unfortunately, I can't get the behavior to work and instead, it just inserts the cursor in the text without selecting what is already there.

I have tried adding a focus Listener to both the JSpinner itself and the text area itself, via ((DefaultEditor) this.getEditor()).getTextField(), yet neither of these seem to have the intended effect. My code (for the JSpinner itself) is as follows:

spinner.addFocusListener(new FocusAdapter(){
            @Override
            public void focusGained(FocusEvent e) {
                ((DefaultEditor) ((JSpinner) e.getSource()).getEditor()).getTextField().selectAll();
            }
        }); 

I'm not sure what the problem is. If it matters, I'm running Mac OS 10.7.5 and Java 6u43.

EDIT: I put a System.out.println right at the beginning of the focusGained method and discovered that it was never called. So it looks like getting focus on the JSpinner isn't registering. Again, I tried putting the focusAdpater both on the spinner and on the text field (not at the same time though).

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<JTextComponent> lstChildren = findAllChildren(spinner, JTextComponent.class);
            if (lstChildren != null && lstChildren.size() > 0) {

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

            }

        }

    }

    public static <T extends Component> List<T> findAllChildren(JComponent component, Class<T> clazz) {

        List<T> lstChildren = new ArrayList<T>(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

Answer 2

Don't know about a Mac but I've used this code on Windows:

JSpinner.DefaultEditor editor = (JSpinner.DefaultEditor)spinner.getEditor();
JTextField textField = editor.getTextField();
textField.addFocusListener( new FocusAdapter()
{
    public void focusGained(final FocusEvent e)
    {
        SwingUtilities.invokeLater(new Runnable()
        {
            @Override
            public void run()
            {
                JTextField tf = (JTextField)e.getSource();
                tf.selectAll();
            }
        });

    }

});

I've also used this code for selecting text on a JFormattedTextField.