feat : decorator pattern

out/production/DesignPatterns/oops/decorator/storyNotes/Note1

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+
+[coffeeShopImpl1] :
+
+    Beverage is an abstract parent class which has two main methods getDescription and getCost. All the child classes
+    inherit from that Beverage class and set its own attributes.
+
+    You can find some items in coffeeShopMenu like ChocoCoffee, ColdCoffee, HotCoffee and couple of hundreds.
+
+    The problem arises where suppose the prices of the coffees increase, also each item can have different configurations
+    like hot coffee with whipped milk or hot coffee with added cream, so there are hundreds of possible permutations.
+
+    One intuition would be to add all these properties in the Beverage Class itself and then just set these booleans on runtime.
+    This approach is represented in Impl2.

src/oops/decorator/coffeeShopImpl1/Beverage.java

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+package oops.decorator.coffeeShopImpl1;
+
+abstract public class Beverage {
+    private String description;
+    private Integer cost;
+
+    public String getDescription() {
+        return description;
+    }
+
+    public Integer getCost() {
+        return cost;
+    }
+
+    public void setDescription(String description) {
+        this.description = description;
+    }
+
+    public void setCost(Integer cost) {
+        this.cost = cost;
+    }
+}

src/oops/decorator/coffeeShopImpl1/coffeeShopMenu/ChocoCoffee.java

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+package oops.decorator.coffeeShopImpl1.coffeeShopMenu;
+
+import oops.decorator.coffeeShopImpl1.Beverage;
+
+public class ChocoCoffee extends Beverage {
+    public ChocoCoffee() {
+        super.setCost(300);
+        super.setDescription("Choco Coffee!!");
+    }
+}

src/oops/decorator/coffeeShopImpl1/coffeeShopMenu/ColdCoffee.java

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+package oops.decorator.coffeeShopImpl1.coffeeShopMenu;
+
+import oops.decorator.coffeeShopImpl1.Beverage;
+
+public class ColdCoffee extends Beverage {
+
+    public ColdCoffee() {
+        super.setCost(200);
+        super.setDescription("Cold Coffee!!");
+    }
+}

src/oops/decorator/coffeeShopImpl1/coffeeShopMenu/HotCoffee.java

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+package oops.decorator.coffeeShopImpl1.coffeeShopMenu;
+
+import oops.decorator.coffeeShopImpl1.Beverage;
+
+public class HotCoffee extends Beverage {
+
+    public HotCoffee() {
+        super.setCost(100);
+        super.setDescription("Hot Coffee!!");
+    }
+
+}

src/oops/decorator/coffeeShopImpl1/coffeeShopMenu/HotCoffeeWithAddedCream.java

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+package oops.decorator.coffeeShopImpl1.coffeeShopMenu;
+
+import oops.decorator.coffeeShopImpl1.Beverage;
+
+public class HotCoffeeWithAddedCream extends Beverage {
+
+    public HotCoffeeWithAddedCream() {
+        Integer hotCoffeeCost = super.getCost();
+        Integer addedCreamCost = 100;
+        super.setCost(hotCoffeeCost + addedCreamCost);
+
+        super.setDescription("Hot Coffee with added cream!!");
+    }
+}

src/oops/decorator/coffeeShopImpl1/coffeeShopMenu/HotCoffeeWithWhippedMilk.java

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+package oops.decorator.coffeeShopImpl1.coffeeShopMenu;
+
+import oops.decorator.coffeeShopImpl1.Beverage;
+
+public class HotCoffeeWithWhippedMilk extends HotCoffee {
+    public HotCoffeeWithWhippedMilk() {
+        Integer hotCoffeeCost = super.getCost();
+        Integer costOfWhippedMilk = 50;
+        super.setCost(hotCoffeeCost + costOfWhippedMilk);
+
+        super.setDescription("Hot Coffee with whipped milk!!");
+    }
+}

src/oops/decorator/coffeeShopImpl2/Beverage.java

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+package oops.decorator.coffeeShopImpl2;
+
+import oops.decorator.coffeeShopImpl2.coffeeShopMenu.CostOfAddons;
+
+abstract public class Beverage {
+
+    private String description;
+    private Integer cost = 0;
+    private Integer costOfProperties = 0;
+
+    public void setDescription(String description) {
+        this.description = description;
+    }
+
+    public void setCost(Integer cost) {
+        this.cost = cost;
+    }
+
+    public String getDescription() {
+        return description;
+    }
+
+    public Integer getTotalCost() {
+        return cost + costOfProperties;
+    }
+
+    public Integer getCostOfProperties() {
+        return costOfProperties;
+    }
+
+    public void notifyPropertiesChanged() {
+        calculateCostOfProperties();
+    }
+
+    private void calculateCostOfProperties() {
+        costOfProperties = 0;
+
+        if (mocha) {
+            costOfProperties += CostOfAddons.mocha;
+        }
+
+        if (choco) {
+            costOfProperties += CostOfAddons.choco;
+        }
+
+        if (cream) {
+            costOfProperties += CostOfAddons.cream;
+        }
+
+        if (whippedMilk) {
+            costOfProperties += CostOfAddons.whippedMilk;
+        }
+
+        // ... and so on
+    }
+
+    ////////// Beverage Properties //////////
+
+    private Boolean mocha = false;
+    private Boolean choco = false;
+    private Boolean cream = false;
+    private Boolean whippedMilk = false;
+    // and 100s of such properties..
+
+    public void setMocha(Boolean mocha) {
+        this.mocha = mocha;
+    }
+
+    public void setChoco(Boolean choco) {
+        this.choco = choco;
+    }
+
+    public void setCream(Boolean cream) {
+        this.cream = cream;
+    }
+
+    public void setWhippedMilk(Boolean whippedMilk) {
+        this.whippedMilk = whippedMilk;
+    }
+}

src/oops/decorator/coffeeShopImpl2/CoffeeShop.java

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+package oops.decorator.coffeeShopImpl2;
+
+import oops.decorator.coffeeShopImpl2.coffeeShopMenu.ChocoCoffee;
+
+public class CoffeeShop {
+    public static void main(String[] args) {
+        Beverage coffee = new ChocoCoffee();
+
+        System.out.println(coffee.getTotalCost());
+
+        // dynamically setting the addons
+
+        coffee.setMocha(true);
+        coffee.setChoco(true);
+        coffee.notifyPropertiesChanged();
+
+        System.out.println(coffee.getTotalCost());
+
+        coffee.setCream(true);
+        coffee.notifyPropertiesChanged();
+
+        System.out.println(coffee.getTotalCost());
+    }
+}

src/oops/decorator/coffeeShopImpl2/coffeeShopMenu/ChocoCoffee.java

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+package oops.decorator.coffeeShopImpl2.coffeeShopMenu;
+
+import oops.decorator.coffeeShopImpl2.Beverage;
+
+public class ChocoCoffee extends Beverage {
+
+    public ChocoCoffee() {
+        super.setCost(100);
+        super.setDescription("Choco Coffee!!");
+    }
+}

src/oops/decorator/coffeeShopImpl2/coffeeShopMenu/CostOfAddons.java

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+package oops.decorator.coffeeShopImpl2.coffeeShopMenu;
+
+public interface CostOfAddons {
+    Integer mocha = 10;
+    Integer choco = 20;
+    Integer cream = 30;
+    Integer whippedMilk = 30;
+}

src/oops/decorator/storyNotes/Note1

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+
+[coffeeShopImpl1] :
+
+    Beverage is an abstract parent class which has two main methods getDescription and getCost. All the child classes
+    inherit from that Beverage class and set its own attributes.
+
+    You can find some items in coffeeShopMenu like ChocoCoffee, ColdCoffee, HotCoffee and couple of hundreds.
+
+    The problem arises where suppose the prices of the coffees increase, also each item can have different configurations
+    like hot coffee with whipped milk or hot coffee with added cream, so there are hundreds of possible permutations.
+
+    One intuition would be to add all these properties in the Beverage Class itself and then just set these booleans on runtime.
+    This approach is represented in Impl2.