Decorator Pattern

Hey there, coding enthusiasts! Today, let’s dive into the exciting world of programming and learn about the amazing “Decorator Pattern.” Don’t worry if it sounds a bit complex – I’m here to break it down for you in simple terms. Imagine you have a plain cupcake, and you want to make it extra special by adding various toppings. Well, that’s exactly what the Decorator Pattern does for your code – it lets you add new features without changing the existing ones. Let’s unwrap this concept and explore it with a Java coding example!

What is the Decorator Pattern, Anyway?

The Decorator Pattern is a nifty trick in programming that helps you modify the behavior of individual objects without altering the entire class structure. It’s like adding layers to a cake – each layer brings something new without changing the cake’s base. In programming, these layers are the decorators, and they wrap around objects to provide extra functionalities.

Sprucing Up with Java: Coding Example

Let’s say we’re building a coffee shop simulator in Java. We have a basic Coffee interface with just one method – getCost(), which returns the cost of a regular coffee. Now, let’s use the Decorator Pattern to add flavors and toppings to our coffee.

First, we create the SimpleCoffee class that implements the Coffee interface. It’s our plain cup of coffee with a cost of $5.

interface Coffee {
    double getCost();
}

class SimpleCoffee implements Coffee {
    public double getCost() {
        return 5.0;
    }
}

Now, let’s add some flavors using decorators. We’ll create a MilkDecorator and a VanillaDecorator, both of which implement the Coffee interface as well. These decorators will wrap around our basic coffee and modify its cost.

class MilkDecorator implements Coffee {
    private Coffee coffee;

    public MilkDecorator(Coffee coffee) {
        this.coffee = coffee;
    }

    public double getCost() {
        return coffee.getCost() + 2.0;  // Adding the cost of milk
    }
}

class VanillaDecorator implements Coffee {
    private Coffee coffee;

    public VanillaDecorator(Coffee coffee) {
        this.coffee = coffee;
    }

    public double getCost() {
        return coffee.getCost() + 3.5;  // Adding the cost of vanilla
    }
}

Now, let’s put all this together! In your main code, you can create your coffee, add decorators to it, and watch the magic happen.

public class Main {
    public static void main(String[] args) {
        Coffee myCoffee = new SimpleCoffee();
        System.out.println("Cost of Simple Coffee: $" + myCoffee.getCost());

        myCoffee = new MilkDecorator(myCoffee);
        System.out.println("Cost of Coffee with Milk: $" + myCoffee.getCost());

        myCoffee = new VanillaDecorator(myCoffee);
        System.out.println("Cost of Coffee with Milk and Vanilla: $" + myCoffee.getCost());
    }
}