Decorator Design Pattern
Aliases 📌: None
Description 📚: A decorator is a class that uses a concrete instance to delegate the implementation of an interface while using its own implementation for one or more methods.
Advantages ✅
- Avoid using inheritance slots (ex: extends in Java)
Disadvantages 🚫
- ???
Notes 📝
- An alternative to inheritance
Java implementation
public interface Food {
String getName();
int getPrice();
default String print() {
return "{ name:" + getName() + ", price:" + getPrice() + " }";
}
}
public class Pizza implements Food {
@Override
public String getName() {
return "Pizza";
}
@Override
public int getPrice() {
return 7;
}
}
public class DriveFood implements Food {
private final Food decorated;
public DriveFood(Food food) {
this.decorated = decorated;
}
@Override
public int getPrice() {
// increase the price
return decorated.getPrice() + 3;
}
@Override
public String getName() {
return decorated.getName();
}
}
public class Main {
public static void main(String[] args) {
Pizza p = new Pizza();
System.out.println(p.print()); // { name:Pizza, price:7 }
DriveFood f = new DriveFood(p);
System.out.println(f.print()); // { name:Pizza, price:10 }
}
}