Coffee Maker

Description

Can you design a coffee maker, that take a coffee pack, and can simply make a cup of coffee.

• Coffee pack contains the recipe of the coffee, like how many milk / how many sugar to be added in the coffee

• Coffee maker can make coffee based on the recipe provided by the coffee pack

• Only consider 2 type of ingredients: sugar and milk

• the cost of Plain coffee is 2. Add one portion of milk/sugar will increase the cost by 0.5

• Consider use decorator design pattern

Example

Input:

pack(2, 3)
makeCoffee()

Output:

Cost for this coffee is: 4.5
Ingredients for this coffee is: Plain Coffee, Milk, Milk, Sugar, Sugar, Sugar

Solution

/**
* This reference program is provided by @jiuzhang.com
* Copyright is reserved. Please indicate the source for forwarding
*/

public class CoffeeMaker {

    public Coffee makeCoffee(CoffeePack pack) {
        Coffee coffee = new SimpleCoffee();

        for (int i = 0; i < pack.getNeededMilk(); i++) {
            coffee = new WithMilk(coffee);
        }

        for (int i = 0; i < pack.getNeededSugar(); i++) {
            coffee = new WithSugar(coffee);
        }

        return coffee;
    }
}

class CoffeePack {
    private int neededMilk;
    private int neededSugar;

    public CoffeePack(int neededMilk, int neededSugar) {
        this.neededMilk = neededMilk;
        this.neededSugar = neededSugar;
    }

    public int getNeededMilk() {
        return neededMilk;
    }

    public int getNeededSugar() {
        return neededSugar;
    }
}

interface Coffee {
    public double getCost();
    public String getIngredients();
}

class SimpleCoffee implements Coffee {

    @Override
    public double getCost() {
        // TODO Auto-generated method stub
        return 2;
    }

    @Override
    public String getIngredients() {
        // TODO Auto-generated method stub
        return "Plain Coffee";
    }

}

abstract class CoffeeDecorator implements Coffee {
    protected final Coffee decoratedCoffee;

    public CoffeeDecorator(Coffee coffee) {
        this.decoratedCoffee = coffee;
    }

    public double getCost() {
        return decoratedCoffee.getCost();
    }

    public String getIngredients() {
        return decoratedCoffee.getIngredients();
    }
}

class WithMilk extends CoffeeDecorator {

    public WithMilk(Coffee coffee) {
        super(coffee);
    }

    public double getCost() {
        return super.getCost() + 0.5;
    }

    public String getIngredients() {
        return super.getIngredients() + ", Milk";
    }
}

class WithSugar extends CoffeeDecorator {

    public WithSugar(Coffee coffee) {
        super(coffee);
    }

    public double getCost() {
        return super.getCost() + 0.5;
    }

    public String getIngredients() {
        return super.getIngredients() + ", Sugar";
    }
}