JSpinner and FocusListener

Question

The method addFocusListener of JSpinner doesn't work. Is it a bug?

Answer 1

No it's not a bug. You might need to try harder to extract from the spinner something that can accept focus:
import java.awt.event.FocusEvent;
import java.awt.event.FocusListener;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JSpinner;
import javax.swing.JTextField;
import javax.swing.SpinnerNumberModel;
public class JSpinFocusListener
  private JPanel mainPanel = new JPanel();
  private JSpinner spinner = new JSpinner(new SpinnerNumberModel(0, -10, 10, 1));
  private JTextField textField = new JTextField(10);
  public JSpinFocusListener()
    mainPanel.add(spinner);
    mainPanel.add(textField);
    // this doesn't work
    spinner.addFocusListener(new MyFocusListener("spinner"));
    // and this doesn't work
    spinner.getEditor().addFocusListener(new MyFocusListener("spinner's editor"));
    // but this one, works
    ((JSpinner.DefaultEditor) spinner.getEditor()).getTextField()
        .addFocusListener(new MyFocusListener("spinner's editor's textfield"));
  public JPanel getMainPanel()
    return mainPanel;
  private class MyFocusListener implements FocusListener
    private String name;
    public MyFocusListener(String name)
      this.name = name;
    public void focusGained(FocusEvent e)
      System.out.println("Focus gained on " + name);
    public void focusLost(FocusEvent e)
      System.out.println("Focus lost from " + name);
  private static void createAndShowUI()
    JFrame frame = new JFrame("JSpinFocusListener");
    frame.getContentPane().add(new JSpinFocusListener().getMainPanel());
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.pack();
    frame.setLocationRelativeTo(null);
    frame.setVisible(true);
  public static void main(String[] args)
    java.awt.EventQueue.invokeLater(new Runnable()
      public void run()
        createAndShowUI();
}