Listen for Changes to the Selected Item in a JComboBox Component in Java

  /*from w  ww .  j  ava 2  s .  c o m*/

import java.awt.BorderLayout;
import java.awt.event.ItemEvent;
import java.awt.event.ItemListener;

import javax.swing.JComboBox;
import javax.swing.JFrame;

public class Main {
  public static void main(String[] argv) throws Exception {
    JFrame frame = new JFrame("Selecting JComboBox");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

    String[] items = { "item1", "item2" };
    JComboBox cb = new JComboBox(items);

    MyItemListener actionListener = new MyItemListener();
    cb.addItemListener(actionListener);
    
    frame.add(cb, BorderLayout.SOUTH);

    frame.setSize(400, 200);
    frame.setVisible(true);
  }
}
class MyItemListener implements ItemListener {
  // This method is called only if a new item has been selected.
  public void itemStateChanged(ItemEvent evt) {
    JComboBox cb = (JComboBox) evt.getSource();

    Object item = evt.getItem();

    if (evt.getStateChange() == ItemEvent.SELECTED) {
      System.out.println("ItemEvent.SELECTED");
      // Item was just selected
    } else if (evt.getStateChange() == ItemEvent.DESELECTED) {
      System.out.println(ItemEvent.DESELECTED);
      // Item is no longer selected
    }
  }
}