package ShoppingCart;

public class Product {

	private String name;

	private int quantity;

	private double unitPrice;

	public Product(String name, int quantity, double unitPrice) {
		this.name=name;
		this.quantity=quantity;
		this.unitPrice=unitPrice;
	}

	public String toString() {
		return name+" "+getQuantity()+" "+getUnitPrice();
	}

	public int getQuantity() {
		return quantity;
	}

	public double getUnitPrice() {
		return unitPrice;
	}

}

package ShoppingCart;

import java.util.Collection;
import java.util.Iterator;
import java.util.Vector;

public class ShoppingCart {

	private Collection products;

	public ShoppingCart() {
		products = new Vector();
	}

	public void addProduct(Product product) {
		products.add(product);
	}

	public String toString() {
		
		Iterator iterator = products.iterator();
		String st = "";
		while (iterator.hasNext()) {
			st += ((Product) iterator.next()).toString() + '\n';
		}
		
		return st;
	}

	public double getTotalValue() {
		
		Iterator iterator = products.iterator();
		double total = 0;
		Product product;
		while (iterator.hasNext()) {
			product = ((Product) iterator.next());
			total += 	product.getQuantity()*product.getUnitPrice();
		}
		
		return total;
	}

	public void clear() {
		products.clear();		
	}
}

import java.applet.Applet;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import ShoppingCart.Product;
import ShoppingCart.ShoppingCart;

public class ShoopingCartApplet extends Applet implements ActionListener {

	private Panel inputPanel;

	private TextField nameTextField;

	private TextField quantityTextField;

	private TextField unitPriceTextField;

	private Button addButton;

	private Button checkOutButton;
	
	private Button checkTotalButton;

	private TextArea outputTextArea;
	
	private TextArea messageTextArea;

	private ShoppingCart shoppingCart;

	public void actionPerformed(ActionEvent e) {
		try {
			if (e.getSource().equals(addButton)) {
				shoppingCart.addProduct(new Product(nameTextField.getText(),
								Integer.parseInt(quantityTextField.getText()),
								Double.parseDouble(unitPriceTextField.getText())));
				outputTextArea.setText("");
				outputTextArea.setText(shoppingCart.toString());		
			} else if (e.getSource().equals(checkTotalButton)){
						outputTextArea.append("Total is: "+shoppingCart.getTotalValue());	
					} else {
						shoppingCart.clear();
						outputTextArea.setText("");
					}
		} catch (NumberFormatException nfe) {
			messageTextArea.setText("INVALID INPUT: " + nfe.toString());
		}
	}

	public void init() {
		shoppingCart = new ShoppingCart();
		inputPanel = new Panel();
		nameTextField = new TextField(15);
		quantityTextField = new TextField(5);
		unitPriceTextField = new TextField(10);
		addButton = new Button("buy");
		checkTotalButton = new Button("check total");
		checkOutButton = new Button("check out");
		outputTextArea = new TextArea(15,90);
		messageTextArea = new TextArea("",5,90,TextArea.SCROLLBARS_NONE);
		
		inputPanel.add(new Label("Product"));
		inputPanel.add(nameTextField);
		inputPanel.add(new Label("Quantity"));
		inputPanel.add(quantityTextField);
		inputPanel.add(new Label("Unit Price"));
		inputPanel.add(unitPriceTextField);
		inputPanel.add(addButton);
		inputPanel.add(checkTotalButton);
		inputPanel.add(checkOutButton);
		
		add(inputPanel);
		add(outputTextArea);
		add(messageTextArea);
		
		addButton.addActionListener(this);
		checkTotalButton.addActionListener(this);
		checkOutButton.addActionListener(this);
	}
}