//------------
// Introduction to Programming Using Java: An Object-Oriented Approach
//	Arnow/Weiss
//------------

//------------
// Chapter 8 / GUI Supplement / Page 305
//	An applet using the Set class
//------------ 

//------------
// Notes
//	- This applet may be run by opening the file 'SetApplet.html'
//		in a browser or appletviewer.
//------------

import java.awt.*;
import java.awt.event.*;
import java.applet.*;
import java.util.*;

public class SetApplet extends Applet 
						implements ActionListener, 
									ItemListener {
	public void init() {
		set1 = new Set();
		set2 = new Set();

		// Components

		setLayout(new BorderLayout());

		// Checkboxes
		set1Selector = new Checkbox("Set 1");
		set1Selector.addItemListener(this);
   		set2Selector = new Checkbox("Set 2");
		set2Selector.addItemListener(this);
		selectorGroup = new CheckboxGroup();
		set1Selector.setCheckboxGroup(selectorGroup);
		set2Selector.setCheckboxGroup(selectorGroup);

		Panel p = new Panel();
		p.add(set1Selector);
		p.add(set2Selector);
		add("North", p);

		// Lists
		set1List = new List();
		set1List.setBackground(Color.white);
		set2List = new List();
		set2List.setBackground(Color.white);
		resultList = new List();
		resultList.setBackground(Color.white);

		p = new Panel();
		p.add(new Label("Set1"));
		p.add(set1List);
		p.add(new Label("Set2"));
		p.add(set2List);
		p.add(new Label("Result"));
		p.add(resultList);
	  	add("Center", p);

		// Buttons
		add = new Button("Add:");
		add.addActionListener(this);
		value = new TextField(5);
		clear = new Button("Clear");
		clear.addActionListener(this);
		union = new Button("Union");
		union.addActionListener(this);
		intersect = new Button("Intersect");
		intersect.addActionListener(this);

		p = new Panel();
		p.add(add);
		p.add(value);
		p.add(clear);
		p.add(union);
		p.add(intersect);
		add("South", p);

		// Set active check box
		selectorGroup.setSelectedCheckbox(set1Selector);
		setActive();
	}

	// Handles action events generated by the buttons
	public void actionPerformed(ActionEvent ae) {
		if (ae.getSource() == add) {
			addElement();
			repaint();
		}
		else if (ae.getSource() == union)
			loadResult(set1.union(set2));
		else if (ae.getSource() == intersect)
			loadResult(set1.intersection(set2));
		else if (ae.getSource() == clear) {
			activeSet.removeAllElements();
			activeList.removeAll();
		}
	}

	// Handles item events generated by the check boxes
	public void itemStateChanged(ItemEvent ie) {
		setActive();
	}

	private void addElement() {
		int i = Integer.parseInt(value.getText());
		activeSet.addElement(new Integer(i));
		activeList.addItem(Integer.toString(i));
	}

  private void setActive() {
		List newActiveList;
		if (selectorGroup.getSelectedCheckbox() == set1Selector) {
			activeList = set1List;
			activeSet = set1;
		}
		else {
			activeList = set2List;
			activeSet = set2;
		}
	}

	private void loadResult(Set resultSet) {
		resultList.removeAll();
		Enumeration e = resultSet.elements();
		while (e.hasMoreElements())
			resultList.addItem(e.nextElement().toString());
		repaint();
	}

	Button add, union, intersect, clear;
	List set1List, set2List, activeList, resultList;
	Checkbox set1Selector, set2Selector;
	CheckboxGroup selectorGroup;
	TextField value;
	Set set1, set2, activeSet;
}