Listening for Action Events from a JComboBox Component

  

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

import javax.swing.JComboBox;

public class Main {
  public static void main(String[] argv) throws Exception {
    String[] items = { "item1", "item2" };
    JComboBox cb = new JComboBox(items);
    cb.setEditable(true);

    // Create and register listener
    MyActionListener actionListener = new MyActionListener();
    cb.addActionListener(actionListener);
  }
}

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

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Listening for Action Events from a JComboBox Component : ComboBox « Swing JFC « Java

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