What is Prototype pattern?

The Prototype pattern is a creational design pattern that enables the creation of objects by cloning or copying existing objects, known as prototypes, rather than creating them from scratch. It specifies a mechanism for creating new objects based on an existing object’s prototype.

The Prototype pattern allows you to create new objects by cloning an existing object, which serves as a blueprint. This approach can be useful when creating new objects is complex, resource-intensive, or requires initialization with specific data. Instead of performing the costly creation or initialization process, you can simply clone an existing object and customize it as needed.

Key components of the Prototype pattern:

  1. Prototype: The prototype is an interface or an abstract class that defines the cloning methods. It declares a method like clone() that serves as a contract for creating copies of objects.
  2. Concrete Prototype: Concrete prototypes are the specific implementations of the prototype interface or class. They implement the cloning method defined in the prototype and provide the actual cloning logic.
  3. Client: The client is responsible for creating new objects by cloning existing prototypes. It interacts with the prototype interface or class and invokes the cloning method to obtain new copies.

Benefits and use cases of the Prototype pattern:

  1. Reduced object creation overhead: The Prototype pattern reduces the overhead of creating complex objects from scratch. Instead of performing expensive initialization or construction processes, you can clone an existing object and customize the clone as needed. This can improve performance and resource utilization.
  2. Flexible object creation: The Prototype pattern provides a way to create objects with different initial configurations or states. By cloning a prototype and modifying its properties, you can create variations of objects without explicitly coding each variation.
  3. Hides the concrete classes from the client: The Prototype pattern hides the concrete classes from the client code. The client only interacts with the prototype interface or abstract class, making the code more flexible and decoupled from specific implementation details.
  4. Dynamic object creation: The Prototype pattern allows for dynamic object creation at runtime. You can create new objects by cloning prototypes based on specific conditions or user input. This provides flexibility in creating objects on the fly.
  5. Maintains consistency across objects: When objects are created by cloning prototypes, they inherit the initial state of the prototype. This helps maintain consistency among objects that belong to the same prototype family, as they share common initial configurations.
  6. Simplifies the creation of complex objects: The Prototype pattern simplifies the creation of complex objects that require the assembly of multiple parts or configurations. By cloning an existing object, you can avoid the complexities of constructing or assembling the object and its dependencies.

Example of the Prototype pattern in Java:

// Prototype interface
public interface Shape extends Cloneable {
    void draw();
    Shape clone();
}

// Concrete prototype 1
public class Circle implements Shape {
    private String color;

    public Circle(String color) {
        this.color = color;
    }

    public void draw() {
        System.out.println("Drawing a circle with color: " + color);
    }

    public Shape clone() {
        return new Circle(color);
    }
}

// Concrete prototype 2
public class Rectangle implements Shape {
    private String color;

    public Rectangle(String color) {
        this.color = color;
    }

    public void draw() {
        System.out.println("Drawing a rectangle with color: " + color);
    }

    public Shape clone() {
        return new Rectangle(color);
    }
}

// Client code
public class Application {
    private List<Shape> shapes;

    public Application() {
        shapes = new ArrayList<>();
    }

    public void addShape(Shape shape) {
        shapes.add(shape);
    }

    public void drawShapes() {
        for (Shape shape : shapes) {
            shape.draw();
        }
    }
}

// Usage:
Application app = new Application();

Shape circle = new Circle("Red");
Shape rectangle = new Rectangle("Blue");

app.addShape(circle);
app.addShape(rectangle);

app.drawShapes();

In the above example, the Prototype pattern is used to create shapes. The Shape interface declares the draw() method and the clone() method for creating copies of shapes. The Circle and Rectangle classes are concrete implementations of the Shape interface and provide the cloning logic in their clone() methods.

The Application class represents the client code that interacts with the shapes. It maintains a list of shapes and provides methods to add shapes and draw them.

In the usage example, a Circle and a Rectangle object are created and added to the Application using the addShape() method. The drawShapes() method is then called to draw all the shapes in the list. Each shape is cloned from the original prototype object, allowing for easy creation of new shape instances with different initial configurations.

By using the Prototype pattern, we avoid the costly process of creating shapes from scratch and instead clone existing shape prototypes. This reduces overhead and simplifies object creation, allowing for flexibility in creating variations of shapes with different colors or properties.

error: Content is protected !!