Why is itemStateChanged on JComboBox is called twice when changed?

Question

I\'m using a JComboBox with an ItemListener on it. When the value is changed, the itemStateChanged event is called twice. The first call, the ItemEvent is showing the origin

Answer 1

The code is:

public class Tester {

    private JComboBox box;

    public Tester() {

        box = new JComboBox();
        box.addItem("One");
        box.addItem("Two");
        box.addItem("Three");
        box.addItem("Four");

        box.addItemListener(new ItemListener() {

            public void itemStateChanged(ItemEvent e) {
                if (e.getStateChange() == 1) {

                    JOptionPane.showMessageDialog(box, e.getItem());
                    System.out.println(e.getItem());
                }
            }
        });

        JFrame frame = new JFrame();
        frame.getContentPane().add(box);
        frame.pack();
        frame.setVisible(true);
    }
}