Listen for Action Events from a JComboBox in Java

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import java.awt.BorderLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

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);
    

    MyActionListener actionListener = new MyActionListener();
    cb.addActionListener(actionListener);
    
    
    frame.add(cb, BorderLayout.SOUTH);

    frame.setSize(400, 200);
    frame.setVisible(true);
    
    
  }
}

class MyActionListener implements ActionListener {
  Object oldItem;

  public void actionPerformed(ActionEvent evt) {
    JComboBox cb = (JComboBox) evt.getSource();
    Object newItem = cb.getSelectedItem();

    boolean same = newItem.equals(oldItem);
    oldItem = newItem;

    if ("comboBoxEdited".equals(evt.getActionCommand())) {
      System.out.println("comboBoxEdited");
      // User has typed in a string; only possible with an editable combobox
    } else if ("comboBoxChanged".equals(evt.getActionCommand())) {
      System.out.println("comboBoxChanged");
      // User has selected an item; it may be the same item
    }
  }
}