import java.awt.BorderLayout;
import java.awt.Container;
import java.awt.ItemSelectable;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.ItemEvent;
import java.awt.event.ItemListener;
import java.io.PrintWriter;
import java.io.StringWriter;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
public class SelectingComboSample {
static private String selectedString(ItemSelectable is) {
Object selected[] = is.getSelectedObjects();
return ((selected.length == 0) ? "null" : (String) selected[0]);
}
public static void main(String args[]) {
String labels[] = { "A", "B", "C", "D","E", "F", "G", "H","J", "I" };
JFrame frame = new JFrame("Selecting JComboBox");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
Container contentPane = frame.getContentPane();
JComboBox comboBox = new JComboBox(labels);
contentPane.add(comboBox, BorderLayout.SOUTH);
final JTextArea textArea = new JTextArea();
textArea.setEditable(false);
JScrollPane sp = new JScrollPane(textArea);
contentPane.add(sp, BorderLayout.CENTER);
ItemListener itemListener = new ItemListener() {
public void itemStateChanged(ItemEvent itemEvent) {
StringWriter sw = new StringWriter();
PrintWriter pw = new PrintWriter(sw);
int state = itemEvent.getStateChange();
String stateString = ((state == ItemEvent.SELECTED) ? "Selected": "Deselected");
pw.print("Item: " + itemEvent.getItem());
pw.print(", State: " + stateString);
ItemSelectable is = itemEvent.getItemSelectable();
pw.print(", Selected: " + selectedString(is));
pw.println();
textArea.append(sw.toString());
}
};
comboBox.addItemListener(itemListener);
ActionListener actionListener = new ActionListener() {
public void actionPerformed(ActionEvent actionEvent) {
StringWriter sw = new StringWriter();
PrintWriter pw = new PrintWriter(sw);
pw.print("Command: " + actionEvent.getActionCommand());
ItemSelectable is = (ItemSelectable) actionEvent.getSource();
pw.print(", Selected: " + selectedString(is));
pw.println();
textArea.append(sw.toString());
}
};
comboBox.addActionListener(actionListener);
frame.setSize(400, 200);
frame.setVisible(true);
}
}