package examples;

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

/**
 * CS401 Example 37
 * 
 * Demonstrates the use of the JList GUI component. The program displays a list
 * of color names in a JList. When the user selects one of them, the background
 * of the window is changed to be that color.
 * 
 * @author PJ Dillon
 */
public class ex37 implements ListSelectionListener
{
	private JList list;
	private Container container;
	private static Color[] colors = {Color.black, Color.WHITE, Color.GREEN, 
		Color.GRAY, Color.BLUE, Color.orange, Color.cyan, Color.magenta,
		Color.yellow, Color.red};
	private static String[] names = {"Black", "White", "Green", "Gray", "Blue",
		"Orange", "Cyan", "Magenta", "Yellow", "Red"};
	
	public ex37()
	{
		JFrame window = new JFrame("Example 37");
		window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		container = window.getContentPane();
		container.setLayout(new FlowLayout());
		
		/*
		 * Create the list is much the same way we created a JComboBox, passing it
		 * an array that initializes its model to display the items passed in.
		 */
		list = new JList(names);
		list.addListSelectionListener(this);
		list.setVisibleRowCount(5);
		
		/*
		 * We want the user to be restricted to only selecting one of the list
		 * values at a time since the background can only be one color at a time.
		 */
		list.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
		
		/*
		 * The list may need more screen space that it can use. If this is the case,
		 * we won't see the part of the list that extends off the window. In this
		 * case, we can use a JScollPane, which is a container that will
		 * automatically display a scroll bar if its component is too large for the
		 * available space.
		 */
		container.add(new JScrollPane(list));
		
		window.setSize(400, 150);
		window.setVisible(true);
	}
	
	/**
	 * The JList component generates a different type of event, a
	 * ListSelectionEvent, which requires a different listener. When an event of 
	 * this type is throw, the valueChanged() method is called of any associated
	 * listeners. 
	 */
	public void valueChanged(ListSelectionEvent e)
	{
		container.setBackground(colors[list.getSelectedIndex()]);
	}
	
	public static void main(String[] args)
	{
		new ex37();
	}
}