import javax.swing.*;
import javax.swing.event.*;
import java.awt.*;
import java.awt.event.*;

public class ComboBoxTest extends JFrame implements ActionListener, ListDataListener,
						    ItemListener {
    JButton add = new JButton("Add");
    JButton remove = new JButton("Remove");
    JTextField text = new JTextField(10);
    JComboBox theBox;
    
    public ComboBoxTest() {
	super("ComboBoxTest");
	addWindowListener(new WindowAdapter() {
		public void windowClosing(WindowEvent e) {
		    System.exit(0);
		}
	    });
	
	String[] theElements = {"one", "two", "three", "four"};
	//Create a combo box containing the String objects above.
	theBox = new JComboBox(theElements);
	theBox.getModel().addListDataListener(this);
	theBox.addActionListener(this);
	theBox.addItemListener(this);
	//Do not show more then three elements.
	theBox.setMaximumRowCount(3);
	
	//Build the UI.
	JPanel addRemove = new JPanel();    
	remove.addActionListener(this);
	addRemove.add(remove);
	add.addActionListener(this);
	addRemove.add(add);
	addRemove.add(text);
	
	Container c = getContentPane();
	c.setLayout(new BorderLayout());
	c.add(addRemove, "North");
	c.add(theBox, "Center");
	
	//Show the frame.
	pack();
	setVisible(true);
    }
    
    public void actionPerformed(ActionEvent e) {
	if (e.getSource() == add) {
	    //Add an element to the list.
	    theBox.addItem(text.getText());
	}
	else if (e.getSource() == remove) {
	    //Remove all elements from the list.
	    theBox.removeAllItems();
	}
	else if (e.getSource() == theBox) {
	    System.out.println("action performed");
	    System.out.println(e.toString() + "\n");
	}
    }
    
    public void itemStateChanged(ItemEvent e) {
	System.out.println("item state changed");
	System.out.println(e.toString() + "\n");
    }
    
    public void intervalAdded(ListDataEvent e) {
	System.out.println("interval added");
	System.out.println(e.toString() + "\n");
    }
    
    public void intervalRemoved(ListDataEvent e) {
	System.out.println("interval removed");
	System.out.println(e.toString() + "\n");
    }
    
    public void contentsChanged(ListDataEvent e) {
	System.out.println("contents changed");
	System.out.println(e.toString() + "\n");
    }
    
    public static void main(String[] args) {
	new ComboBoxTest();
    }
}