Product.java

package problem10;

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;

/**
 *
 * @author bas
 */

public class Product {

	private String name;
	private double price;

	public Product(String name, double price) {
		setName(name);
		setPrice(price);
	}

	public String getName() {
		return name;
	}

	public void setName(String name) {
		if (name.equals(" ")) {
			this.name = "not entered";
		} else {
			this.name = name;
		}
	}

	public double getPrice() {
		return price;
	}

	public void setPrice(double price) {
		if (price < 0) {
			this.price = 0;
		} else {
			this.price = price;
		}
	}

	public static void writeBill() {
		try {
			BufferedWriter out = new BufferedWriter(new FileWriter(
					"Output.txt"));
			out.write(String.format("%.2f", calculateTotalBill()));
			out.close();
		} catch (Exception e) {
			e.printStackTrace();
		}
	}

	public static Product[] extractProducts() {
		FileReader fr;

		try {
			fr = new FileReader("Products.txt");

			BufferedReader br = new BufferedReader(fr);

			int numLines = countLines("Products.txt");
			Product[] products = new Product[numLines];
			String[] info = new String[2];
			for (int i = 0; i < numLines; i++) {
				String current = br.readLine();
				info = current.split(" ");

				products[i] = new Product(" ", 0);
				products[i].setName(info[0].toString());
				products[i].setPrice(Double.parseDouble(info[1]));
			}
			fr.close();
			return products;
		} catch (Exception e) {

			e.printStackTrace();
		}
		return null;
	}

	public static double calculateTotalBill() {
		FileReader fr;
		double bill = 0;
		try {
			fr = new FileReader("Order.txt");
			BufferedReader br = new BufferedReader(fr);
			int numLines = countLines("Order.txt");

			Product[] products = extractProducts();

			for (int i = 0; i < numLines; i++) {
				String[] orderInfo = br.readLine().split(" ");
				for (int j = 0; j < products.length; j++) {
					if (orderInfo[1].equals(products[j].getName())) {
						bill += products[j].getPrice()
								* Double.parseDouble(orderInfo[0]);
					}
				}
			}

			fr.close();
		} catch (Exception e) {

			e.printStackTrace();
		}

		return bill;
	}

	public static int countLines(String file) throws IOException {
		FileReader fr = new FileReader(file);
		BufferedReader br = new BufferedReader(fr);

		String aLine = br.readLine();
		int numberOfLines = 0;

		while ((aLine) != null) {
			numberOfLines++;
			aLine = br.readLine();
		}
		br.close();
		return numberOfLines;
	}

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

}