2906. Design Pattern - PrototypePrototype Pattern
Creational Pattern: Prototype Pattern.
1. Prototype Pattern
Prototype pattern refers to creating duplicate object while keeping performance in mind. Specify the kinds of objects to create using a prototypical instance, and create new objects by copying this prototype.
2. Example of Implementation
2.1 Base Class
public abstract class Shape implements Cloneable {
private String id;
protected String type;
abstract void draw();
public String getType(){
return type;
}
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public Object clone() {
Object clone = null;
try {
clone = super.clone();
} catch (CloneNotSupportedException e) {
e.printStackTrace();
}
return clone;
}
}
2.2 Classes
public class Circle extends Shape {
public Circle(){
type = "Circle";
}
@Override
public void draw() {
System.out.println("Shape: Circle");
}
}
public class Rectangle extends Shape {
public Rectangle(){
type = "Rectangle";
}
@Override
public void draw() {
System.out.println("Shape: Rectangle");
}
}
public class Square extends Shape {
public Square(){
type = "Square";
}
@Override
public void draw() {
System.out.println("Shape: Square");
}
}
2.3 Usage
public class ShapeCache {
private static Map<String, Shape> mapShape = new HashMap<>();
public static Shape getShape(String shapeId) {
Shape cachedShape = mapShape.get(shapeId);
return (Shape) cachedShape.clone();
}
public static void loadCache() {
Circle circle = new Circle();
circle.setId("1");
mapShape.put(circle.getId(), circle);
Square square = new Square();
square.setId("2");
mapShape.put(square.getId(), square);
Rectangle rectangle = new Rectangle();
rectangle.setId("3");
mapShape.put(rectangle.getId(), rectangle);
}
}
Get new object from cache without directly creating new instance.
public class Client {
public void run() {
ShapeCache.loadCache();
Shape clonedShape = (Shape) ShapeCache.getShape("1");
System.out.println("Shape : " + clonedShape.getType());
Shape clonedShape2 = (Shape) ShapeCache.getShape("2");
System.out.println("Shape : " + clonedShape2.getType());
Shape clonedShape3 = (Shape) ShapeCache.getShape("3");
System.out.println("Shape : " + clonedShape3.getType());
}
}
Output.
Shape : Circle
Shape : Square
Shape : Rectangle