// This demo shows only a few variations of the "Swing" graphical objects
//  used in this program; there are many more, especially involving the
//  'JList' class

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

public class JFrameJMenuJSliderJComboJList extends JFrame
														 implements ActionListener, ChangeListener, ListSelectionListener
{
	// Objects that need to be referenced from outside the constructor
	//  must be defined here (so that they are global to the class)
	private JSlider slider;
	private JComboBox combo;
	private JList list;
	private DefaultListModel listModel;
	private JScrollPane listScrollPane;
	private JTextField textList, textCombo;
	private JButton buttonAddToCombo, buttonRemoveFromCombo, buttonClearCombo;
	private JButton buttonAddToList, buttonRemoveFromList, buttonClearList;

	static final int SLIDER_MIN = 0;
	static final int SLIDER_MAX = 30;
	static final int SLIDER_INIT = 15;
	boolean editInProgress = false;

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

	// Constructor
	public JFrameJMenuJSliderJComboJList()
	{
		// Note that it is NOT necessary to explicitly create a 'JFrame' object
		//  here, since extending the 'JFrame' class does that automatically

		// Allow objects to be placed anywhere on the JFrame
		setLayout(null);

		// Don't let the JFrame be resized
		setResizable(false);

		// Allow the JFrame to be closed via the "X" 
		setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

		// Set the size, title, and background color of the JFrame
		setSize(440, 460);
		setTitle("Demo #4:  JFrame, JMenuBar, JSlider, JComboBox, & JList");
		getContentPane().setBackground(Color.BLACK);

		// Position the JFrame in the center of the screen
		setLocationRelativeTo(null);

		//=============================================================================//

		// Create a JMenuBar
		JMenuBar menuBar = new JMenuBar();

		// Create two (top level) JMenus
		JMenu fileMenu = new JMenu("File");
		JMenu helpMenu = new JMenu("Help");

		// Create three JCheckBoxMenuItems and two JMenuItems and allow them to
		//  respond to user actions
		JCheckBoxMenuItem sliderMenuItem = new JCheckBoxMenuItem("Show JSlider");
		sliderMenuItem.setActionCommand("slider");
		sliderMenuItem.addActionListener(this);

		JCheckBoxMenuItem comboBoxMenuItem = new JCheckBoxMenuItem("Show JComboBox");
		comboBoxMenuItem.setActionCommand("combo");
		comboBoxMenuItem.addActionListener(this);

		JCheckBoxMenuItem listMenuItem = new JCheckBoxMenuItem("Show JList");
		listMenuItem.setActionCommand("list");
		listMenuItem.addActionListener(this);

		JMenuItem exitMenuItem = new JMenuItem("Exit");
		exitMenuItem.setActionCommand("exit");
		exitMenuItem.addActionListener(this);

		JMenuItem aboutMenuItem = new JMenuItem("About...");
		aboutMenuItem.setActionCommand("about");
		aboutMenuItem.addActionListener(this);

		// Add the above JMenuItems, and separators, to the two JMenus
		fileMenu.add(sliderMenuItem);
		fileMenu.addSeparator();
		fileMenu.add(comboBoxMenuItem);
		fileMenu.add(listMenuItem);
		fileMenu.addSeparator();
		fileMenu.add(exitMenuItem);

		helpMenu.add(aboutMenuItem);

		// Add the two JMenus to the JMenuBar 
		menuBar.add(fileMenu);
		menuBar.add(helpMenu);

		// Add the JMenuBar to the JFrame
		setJMenuBar(menuBar);

		//=============================================================================//

		// Create and set up a JSlider
		slider = new JSlider(JSlider.HORIZONTAL, SLIDER_MIN, SLIDER_MAX, SLIDER_INIT);
		slider.setLocation(27, 25);
		slider.setSize(380, 50);
		slider.setMinorTickSpacing(1);
		slider.setMajorTickSpacing(3);
		slider.setPaintTicks(true);
		slider.setPaintLabels(true);
		slider.setVisible(false);

		// Allow the JSlider to respond to actions and add it to the JFrame
		slider.addChangeListener(this);
		add(slider);

		//=============================================================================//

		// Create and set up a JComboBox
		String[] comboData = {"cat", "dog", "fish", "ant", "bee", "shark", "zebra", "elephant"};
		combo = new JComboBox(comboData);

		combo.setLocation(27, 100);
		combo.setSize(90, 20);
		combo.setVisible(false);

		// Set the index of the JComboBox item that should be initially highlighted; to
		//  start off with NO element highlighted, use the value of -1
		combo.setSelectedIndex(0);

		// Allow the JComboBox to respond to actions and add it to the JFrame
		combo.addActionListener(this);
		add(combo);

		//=============================================================================//

		textCombo = new JTextField();
		textCombo.setLocation(256, 100);
		textCombo.setSize(150, 20);
		textCombo.setHorizontalAlignment(JTextField.CENTER);
		textCombo.setVisible(false);
		add(textCombo);

		buttonAddToCombo = new JButton("Add Element");
		buttonAddToCombo.setLocation(256, 125);
		buttonAddToCombo.setSize(150, 20);
		buttonAddToCombo.setVisible(false);
		add(buttonAddToCombo);

		buttonRemoveFromCombo = new JButton("Remove Element");
		buttonRemoveFromCombo.setLocation(256, 150);
		buttonRemoveFromCombo.setSize(150, 20);
		buttonRemoveFromCombo.setVisible(false);
		add(buttonRemoveFromCombo);

		buttonClearCombo = new JButton("Clear ComboBox");
		buttonClearCombo.setLocation(256, 175);
		buttonClearCombo.setSize(150, 20);
		buttonClearCombo.setVisible(false);
		add(buttonClearCombo);

		buttonAddToCombo.addActionListener(new ActionListener()
		{
			public void actionPerformed(ActionEvent event)
			{
				if (!textCombo.getText().trim().equals(""))
					combo.insertItemAt(textCombo.getText().trim(), combo.getSelectedIndex() + 1);
				// combo.addItem(textCombo.getText().trim()); <-- Use to always add at END of box
			}
		});

		buttonRemoveFromCombo.addActionListener(new ActionListener()
		{
			public void actionPerformed(ActionEvent event)
			{
				// Whenever an item is removed from the JComboBox, another item in
				//  the JComboBox (usually the item immediately preceding the removed
				//  item) is automatically selected; this, in turn, triggers the
				//  'actionPerformed' method; the variable 'editInProgress' is used
				//  to prevent unwanted output from the 'actionPerformed' method
				editInProgress = true;
				if (combo.getSelectedIndex() > -1)
					combo.removeItemAt(combo.getSelectedIndex());
			}
		});

		buttonClearCombo.addActionListener(new ActionListener()
		{
			public void actionPerformed(ActionEvent event)
			{
				combo.removeAllItems();
			}
		});

		//=============================================================================//

		// Create a JList and assign to it a DefaultListModel
		listModel = new DefaultListModel();
		list = new JList(listModel);

		// Note that the JList is useful for displaying static data, but to add,
		//  remove, or change elements, a DefaultListModel (or AbstractListModel or
		//  ListModel) must be used, and the JList will automatically reflect any
		//  changes made; while this approach may be confusing at first, its purpose
		//  is to break the list management process into a read-only component and a
		//  writable component, allowing the first to exist without the second

		String[] listData = {"cat", "dog", "fish", "ant", "bee", "shark", "zebra", "elephant", "whale",
									"aardvark", "goat", "porcupine", "walrus", "giraffe", "crocodile"};
		for (String element : listData)
			listModel.addElement(element);

		// Set the number of JList columns to be used for displaying data (VERTICAL,
		//  VERTICAL_WRAP, or HORIZONTAL_WRAP)
		list.setLayoutOrientation(JList.VERTICAL);

		// Set the number of rows in the JList that are visible without scrolling;
		//  note that if the dimensions of the JScrollPane (below) are manually set
		//  (if a 'null' layout manager is used), then this next line will have no
		//  effect 
		list.setVisibleRowCount(5);

		// Set the index of the JList item that should be initially highlighted;
		//  the value of -1 is used to start off with NO element highlighted
		list.setSelectedIndex(-1);

		// Determine how many JList items the user is able to select (highlight)
		//  at one time (SINGLE_SELECTION, SINGLE_INTERVAL_SELECTION, or
		//  MULTIPLE_INTERVAL_SELECTION)
		list.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);

		// Allow the JList to respond to actions
		list.addListSelectionListener(this);

		// Create and set up a JScrollPane, and add the JList to it; a JScrollPane
		//  provides a scrollable view of a component, so using a JScrollPane here
		//  allows the user to see and easily access large numbers of data items
		listScrollPane = new JScrollPane(list);
		listScrollPane.setLocation(27, 290);
		listScrollPane.setSize(90, 94);
		listScrollPane.setVisible(false);

		// Add the JScrollPane to the JFrame
		add(listScrollPane);

		//=============================================================================//

		textList = new JTextField();
		textList.setLocation(256, 290);
		textList.setSize(150, 20);
		textList.setHorizontalAlignment(JTextField.CENTER);
		textList.setVisible(false);
		add(textList);

		buttonAddToList = new JButton("Add Element");
		buttonAddToList.setLocation(256, 315);
		buttonAddToList.setSize(150, 20);
		buttonAddToList.setVisible(false);
		add(buttonAddToList);

		buttonRemoveFromList = new JButton("Remove Element");
		buttonRemoveFromList.setLocation(256, 340);
		buttonRemoveFromList.setSize(150, 20);
		buttonRemoveFromList.setVisible(false);
		add(buttonRemoveFromList);

		buttonClearList = new JButton("Clear List");
		buttonClearList.setLocation(256, 365);
		buttonClearList.setSize(150, 20);
		buttonClearList.setVisible(false);
		add(buttonClearList);

		buttonAddToList.addActionListener(new ActionListener()
		{
			public void actionPerformed(ActionEvent event)
			{
				if (!textList.getText().trim().equals(""))
					listModel.insertElementAt(textList.getText().trim(), list.getSelectedIndex() + 1);
				// listModel.addElement(textList.getText().trim()); <-- Use to always add to END of list
			}
		});

		buttonRemoveFromList.addActionListener(new ActionListener()
		{
			public void actionPerformed(ActionEvent event)
			{
				if (list.getSelectedIndex() > -1)
					listModel.removeElementAt(list.getSelectedIndex());
			}
		});

		buttonClearList.addActionListener(new ActionListener()
		{
			public void actionPerformed(ActionEvent event)
			{
				listModel.clear();
			}
		});

		//=============================================================================//

		// Make the JFrame (and everything on it) visible; note that this line
		//  is executed AFTER the above objects have been added to the JFrame
		//  to ensure that all of the above added objects appear on the JFrame 
		setVisible(true);
	}

	//================================================================================//

	// This method is called whenever one of the JMenuItems is selected, as well
	//  as when the selected item in the JComboBox has changed
	public void actionPerformed(ActionEvent event)
	{
		if (event.getActionCommand() == "slider")
		{
			slider.setVisible(!slider.isVisible());
			return;
		}

		if (event.getActionCommand() == "combo")
		{
			combo.setVisible(!combo.isVisible());
			textCombo.setVisible(!textCombo.isVisible());
			buttonAddToCombo.setVisible(!buttonAddToCombo.isVisible());
			buttonRemoveFromCombo.setVisible(!buttonRemoveFromCombo.isVisible());
			buttonClearCombo.setVisible(!buttonClearCombo.isVisible());
			textCombo.requestFocus();
			return;
		}

		// If the JComboBox selected item has changed, display both the index of
		//  the item and the item itself
		if (event.getActionCommand() == "comboBoxChanged")
		{
			// If a JComboBox item is not currently in the process of being
			//  selected, display the newly selected value
			if (!editInProgress && combo.getSelectedIndex() > -1)
			{
				System.out.print("ComboBox Index:  " + combo.getSelectedIndex() + "        ");
				System.out.println("ComboBox Item:  " + combo.getSelectedItem());
			}
			editInProgress = false;
		}

		if (event.getActionCommand() == "list")
		{
			listScrollPane.setVisible(!listScrollPane.isVisible());
			textList.setVisible(!textList.isVisible());
			buttonAddToList.setVisible(!buttonAddToList.isVisible());
			buttonRemoveFromList.setVisible(!buttonRemoveFromList.isVisible());
			buttonClearList.setVisible(!buttonClearList.isVisible());
			textList.requestFocus();
			return;
		}

		if (event.getActionCommand() == "about")
		{
			System.out.println("Choose options from the 'File' pulldown menu to see more examples of \"Swing\" objects.");
			return;
		}

		if (event.getActionCommand() == "exit")
			System.exit(0);
	}

	//================================================================================//

	// This method is called whenever the value of the JSlider is changed
	public void stateChanged(ChangeEvent event)
	{
		// If the JSlider value is not currently in the process of being adjusted,
		//  display the newly selected value
		JSlider sliderSource = (JSlider) event.getSource();
		if (!sliderSource.getValueIsAdjusting())
			System.out.println("Slider Value:  " + sliderSource.getValue());
	}

	//================================================================================//

	// This method is called whenever an item is selected from the JList
	public void valueChanged(ListSelectionEvent event)
	{
		// Since this method appears to be called when the user clicks on a JList
		//  item, as well as when the data value is officially selected, make sure
		//  the first occurrence of each click is ignored so that the newly selected
		//  value is not displayed twice; also make sure no values are displayed
		//  after an element is removed from the JList
		if (!list.getValueIsAdjusting() && list.getSelectedIndex() > -1)
		{
			System.out.print("List Index:  " + list.getSelectedIndex() + "        ");
			System.out.println("List Item:  " + list.getSelectedValue());
		}
	}
}