Decorator design pattern - AFTER CODE with cake decorator to avoid cr…

…eating class for each option.

Benefits
1. Lean code - as its not required to create class for each option
2. Price can be calculated dynamically
3. Performance improvement
4. Loose coupling.
5. Easy to update - price of can be updated at one place without touching other classes.

pattern/src/com/premaseem/Client.java

@@ -14,6 +14,27 @@ public static void main (String[] args) {
  Cake cake = new VanillaCake();
  System.out.println("Plain cake price without decorations - "+ cake.getCost());
 
+ // Decorated Object with addons
+ cake = new CandyDecoration(cake);
+ System.out.println("Cake price with Candy decoration - "+ cake.getCost());
+
+ // Decorated Object with addons
+ // Fun side, price of Cartoon decoration is more then cake itself :-)
+ cake = new CartoonDecoration(cake);
+ cake = new CartoonDecoration(cake);
+ System.out.println("Cake price with double Cartoon decoration - "+cake.getCost());
+
+
+ /* TAKE AWAY:
+ 1. Lean code - as its not required to create class for each option
+ 2. Price can be calculated dynamically
+ 3. Performance improvement
+ 4. Loose coupling.
+ 5. Easy to update - price of can be updated at one place without touching other classes.
+
+ */
+
+ /* OLD DISCARDED CODE
  // with decoration
  cake = new VanillaCakeWithCandyDecoration();
  System.out.println("Cake price with Candy decoration - "+ cake.getCost());
@@ -25,10 +46,9 @@ public static void main (String[] args) {
  // with multiple decorations
  cake = new VanillaCakeWithCandyAndCartoonDecoration();
  System.out.println("Cake price with Candy and Cartoon decoration - "+ cake.getCost());
+ */
 
-
- /*
- Take Away from Bad Code:
+ /*Take Away from Bad Code:
  1. For each combination/ option there is a static class.
  2. With less options its ok but in real cake software time application will
  blow out of proportion due to so many classes.

pattern/src/com/premaseem/Decoration.java

@@ -0,0 +1,54 @@
+package com.premaseem;
+
+/*
+@author: Aseem Jain
+@title: Design Patterns with Java 9
+@link: https://premaseem.wordpress.com/category/computers/design-patterns/
+*/
+
+public abstract class Decoration extends Cake{
+ Cake cake;
+
+ @Override
+ String getIngredients () {
+ return "decoration using different addon items";
+ }
+}
+
+class CandyDecoration extends Decoration{
+
+ Cake baseCake;
+
+ public CandyDecoration (Cake cake) {
+ baseCake = cake;
+ }
+
+ @Override
+ double getCost () {
+ return baseCake.getCost() + .12;
+ }
+
+ @Override
+ String getIngredients () {
+ return "decoration using candies";
+ }
+}
+
+class CartoonDecoration extends Decoration{
+
+ Cake baseCake;
+
+ public CartoonDecoration (Cake cake) {
+ baseCake = cake;
+ }
+
+ @Override
+ double getCost () {
+ return baseCake.getCost() + 2.32;
+ }
+
+ @Override
+ String getIngredients () {
+ return "decoration using candies";
+ }
+}