package examples;

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

/**
 * CS401 Example 36c
 * 
 * Demonstrates the use of a JComboBox GUI component. A combo box can work much
 * like a group of radio buttons in that it displays a set of options from which
 * the user can select only one at a time. It, however, can take up far less 
 * screen space since the available options are only displayed when the user
 * clicks a downward pointing arrow to show a popup list containing the options.
 * 
 * Additionally, the JComboBox can provide the means for the user to enter a new
 * value for the list. The setEditable() method enables this functionality.
 * This program would through
 * 
 * @author PJ Dillon
 */
public class ex36c implements ActionListener
{
	private int[] styles = {Font.PLAIN, Font.BOLD, Font.ITALIC, 
													Font.BOLD+Font.ITALIC};
	private JLabel label;
	private JComboBox box;
	
	public ex36c()
	{
		JFrame window = new JFrame("Example 36c");
		window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		Container c = window.getContentPane();
		c.setLayout(new FlowLayout());
		
		label = new JLabel("Text To Change");
		label.setFont(new Font("TimesRoman", Font.PLAIN, 72));
		c.add(label);
		
		/*
		 * The combobox maintains an internal group of items it's currently storing, 
		 * typicially called the component's model, which renders as the list 
		 * displayed when the user clicks the drop down button. One of the JComboBox
		 * constructors accepts an array of objects that initialize this group,
		 * meaning the array is the list of Objects displayed.
		 */
		String[] names = {"Plain", "Bold", "Italics", "Bold/Italics"};
		box = new JComboBox(names);
		box.addActionListener(this);
		c.add(box);

		/*
		 * By setting the combo box to be editable, we give the user the ability to
		 * enter new values into the combo box area on the screen. These values are
		 * automatically added to the list in the combo box.
		 */
		//box.setEditable(true);
		
		/*
		 * The setMaximumRowCount() method limits the size of the drop down list to
		 * only display the number of items specified here. If there are more items
		 * in the list, a scroll bar is automatically shown for the user. Setting
		 * this value can give your code a nicer feel. 
		 */
		box.setMaximumRowCount(3);
		
		window.setSize(520, 200);
		window.setVisible(true);
	}

	public void actionPerformed(ActionEvent e)
	{
		/*
		 * If the combobox is set to editable and the user enters a new value into 
		 * it, this line will throw an exception because the new value is not
		 * automatically added to combo box list, making the call to
		 * getSelectedIndex() return -1. 
		 */
		label.setFont(new Font("TimesRoman", styles[box.getSelectedIndex()], 72));
	}

	public static void main(String[] args)
	{
		new ex36c();
	}
}