Changed the ProductCatalog's usage to follow the Singleton pattern.

By refactoring the class ProductCatalog as an implementation of the Singleton
pattern, we're able to avoid any issues coming from the instantiation
of the list of products, which is now made the first time someone uses
any method from the class.

Author: ProgrammingKiddo

src/main/java/coreapi/Menu.java

@@ -66,12 +66,12 @@ public List<Product> getProductsInMenu()
 	 */
 	public int getProductQuantity(int productId)
 	{
-		Product productToCheck = ProductCatalog.getProduct(productId);
+		Product productToCheck = ProductCatalog.Instance().getProduct(productId);
 		int productQuantity;
 
 		if (productsMenu.containsKey(productToCheck))
 		{
-			productQuantity = productsMenu.get(ProductCatalog.getProduct(productId)).intValue();			
+			productQuantity = productsMenu.get(ProductCatalog.Instance().getProduct(productId)).intValue();			
 		}
 		else
 		{

src/main/java/coreapi/OrderImpl.java

@@ -64,7 +64,7 @@ public Map<Product,Integer> getBasket()
 	 */
 	public boolean containsProduct(int id)
 	{
-		return basket.containsKey(ProductCatalog.getProduct(id));
+		return basket.containsKey(ProductCatalog.Instance().getProduct(id));
 	}
 
 	/**
@@ -76,7 +76,7 @@ public int checkProductQuantity(int id)
 
 		if (this.containsProduct(id))
 		{
-			quantity = basket.get(ProductCatalog.getProduct(id)).intValue();
+			quantity = basket.get(ProductCatalog.Instance().getProduct(id)).intValue();
 		}
 		else
 		{
@@ -94,7 +94,7 @@ public void addProduct(int newProductId, int quantity)
 	{
 		if (quantity > 0)
 		{
-			Product prod = ProductCatalog.getProduct(newProductId);
+			Product prod = ProductCatalog.Instance().getProduct(newProductId);
 			if (this.containsProduct(newProductId))
 			{
 				int actualQuantity = basket.get(prod).intValue();
@@ -109,14 +109,14 @@ public void addProduct(int newProductId, int quantity)
 
 	public void removeProduct(int productId)
 	{
-		basket.remove(ProductCatalog.getProduct(productId));
+		basket.remove(ProductCatalog.Instance().getProduct(productId));
 	}
 
 	public void removeProduct(int productId, int quantity)
 	{
 		if (quantity > 0)
 		{
-			Product prod = ProductCatalog.getProduct(productId);
+			Product prod = ProductCatalog.Instance().getProduct(productId);
 			if (basket.get(prod).intValue() <= quantity)
 			{
 				this.removeProduct(productId);

src/main/java/coreapi/OrderService.java

@@ -17,7 +17,7 @@ public OrderService() {}
 	 */
 	public void addProductToOrder(Cafeteria coffe, OrderImpl ord, int productId, int q)
 	{
-		Product prod = ProductCatalog.getProduct(productId);
+		Product prod = ProductCatalog.Instance().getProduct(productId);
 		if(ord.containsProduct(productId))
 		{
 			throw new RuntimeException("This product is already in your basket, you can modify the quantity of it if you wish.");
@@ -45,7 +45,7 @@ public void addProductToOrder(Cafeteria coffe, OrderImpl ord, int productId, int
 	 */
 	public void modifyProductQuantity(Cafeteria coffe, OrderImpl ord, int productId, int q)
 	{
-		Product prod = ProductCatalog.getProduct(productId);
+		Product prod = ProductCatalog.Instance().getProduct(productId);
 
 		if(coffe.productStock.containsKey(prod) && ord.containsProduct(productId))
 		{

src/main/java/coreapi/ProductCatalog.java

@@ -1,11 +1,37 @@
+/**
+ * The <code>ProductCatalog</code> class works as a placeholder for product
+ * data representation, as it will come later pre-established as a file.
+ * @author Borja
+ * @version 0.2
+ * @see Product
+ */
+
 package coreapi;
 
 
 public class ProductCatalog {
 
 	private static Product[] products = new Product[10];
+	private static ProductCatalog uniqueInstance;
 
-	public static void createProducts()
+	/**
+	 * Returns the unique existing instance of the <code>ProductCatalog</code> class,
+	 * through which the user is able to call its methods.
+	 * @return the only instance of the class.
+	 */
+	public static ProductCatalog Instance()
+	{
+		if (uniqueInstance == null)
+		{
+			uniqueInstance = new ProductCatalog();
+		}
+		return uniqueInstance;
+	}
+	/**
+	 * This private constructor initializes the list of products that serves as a
+	 * temporary placeholder for product information.
+	 */
+	private ProductCatalog()
 	{
 		products[0] = new ProductImpl(0, (float) 1.2, "Patatas fritas");
 		products[1] = new ProductImpl(1, (float) 1.7, "Bacon-queso-huevo");
@@ -18,8 +44,12 @@ public static void createProducts()
 		products[8] = new ProductImpl(8, (float) 0.75, "Donut de chocolate");
 		products[9] = new ProductImpl(9, (float) 1.4, "Sándwich de roquefort");
 	}
-	
-	public static Product getProduct(int id)
+	/**
+	 * Returns the corresponding reference to a certain product, determined by its identifier.
+	 * @param id the product identifier number to check for.
+	 * @return the product corresponding to the id passed as a parameter.
+	 */
+	public Product getProduct(int id)
 	{
 		if (id <= 9 && id >= 0)
 		{

src/test/java/coreapiTest/MenuTest.java

@@ -15,8 +15,8 @@
 public class MenuTest
 {
 	private Menu myMenu;
-	private Product product1 = ProductCatalog.getProduct(0);
-	private Product product2 = ProductCatalog.getProduct(1);
+	private Product product1 = ProductCatalog.Instance().getProduct(0);
+	private Product product2 = ProductCatalog.Instance().getProduct(1);
 
 	@Before
 	public void setUp()

src/test/java/coreapiTest/OrderImplTest.java

@@ -14,8 +14,8 @@ public class OrderImplTest {
 
 	private OrderImpl myOrder;
 
-	private Product product1 = ProductCatalog.getProduct(0);
-	private Product product2 = ProductCatalog.getProduct(1);
+	private Product product1 = ProductCatalog.Instance().getProduct(0);
+	private Product product2 = ProductCatalog.Instance().getProduct(1);
 
 	@Before
 	public void setUp()

src/test/java/coreapiTest/OrderServiceTest.java

@@ -35,9 +35,9 @@ protected void setUp()
 		ordSer = new OrderService();
 
 		// We introduce products from the catalog to the cafeteria with a certain stock
-		Product1 = ProductCatalog.getProduct(0);
-		Product2 = ProductCatalog.getProduct(1);
-		Product3 = ProductCatalog.getProduct(2);
+		Product1 = ProductCatalog.Instance().getProduct(0);
+		Product2 = ProductCatalog.Instance().getProduct(1);
+		Product3 = ProductCatalog.Instance().getProduct(2);
 		coffe.ProductRegister(Product1, 10);
 		coffe.ProductRegister(Product2, 8);
 		coffe.ProductRegister(Product3, 30);

src/test/java/coreapiTest/ProductImplTest.java

@@ -18,9 +18,9 @@ public class ProductImplTest
 	@Before
 	public void setUp()
 	{
-		Product1 = (ProductImpl) ProductCatalog.getProduct(0);
-		Product2 = (ProductImpl) ProductCatalog.getProduct(1);
-		Product3 = (ProductImpl) ProductCatalog.getProduct(2);
+		Product1 = (ProductImpl) ProductCatalog.Instance().getProduct(0);
+		Product2 = (ProductImpl) ProductCatalog.Instance().getProduct(1);
+		Product3 = (ProductImpl) ProductCatalog.Instance().getProduct(2);
 	}
 
 	@After

src/test/java/coreapiTest/ProductTest.java

@@ -16,9 +16,9 @@ public class ProductTest
 	@Before
 	public void setUp()
 	{
-		Product1 = ProductCatalog.getProduct(3);
-		Product2 = ProductCatalog.getProduct(4);
-		Product3 = ProductCatalog.getProduct(5);
+		Product1 = ProductCatalog.Instance().getProduct(3);
+		Product2 = ProductCatalog.Instance().getProduct(4);
+		Product3 = ProductCatalog.Instance().getProduct(5);
 	}
 
 	@After

src/test/java/coreapiTest/TestRunner.java

@@ -11,7 +11,6 @@ public class TestRunner
 {
 	public static void main(String[] args)
 	{
-		ProductCatalog.createProducts();
 		Result result = JUnitCore.runClasses(CoffeeShopTestSuite.class);
 		for(Failure failure : result.getFailures())
 		{