The Prototype Pattern
The Prototype Pattern:
This pattern enables you
to copy or clone of an existing object instead of creating the new one and may
also customized as per the requirement. It copies the existing object to avoid so much overhead. We can also use the clone method by implementing the
Clonable interface to create the copy of the existing object.
Benefits: It supports for specifying the new
objects with varying structure and varying values, adding and removing products
at runtime, dynamically configuring the classes for an application and reducing
sub-classing.
Usage: These are used when you are not
interested in constructing a class hierarchy of factories which is parallel to
the class hierarchy of products. Instances of a class can have only one
combination of state, the classes are instantiated at run-time.
Example: Let's create an interface and implement
it in the various classes.
Shape.java
|
interface Shape {
public void draw();
}
|
Square.java
class Square implements Shape {
public void draw() {
System.out.println("square");
}
} |
Circle.java
class Circle implements Shape {
public void draw() {
System.out.println("circle");
}
} |
Painting.java
class Painting {
public static void main(String[] args) {
Shape s = new Square();
Shape c = new Circle();
paint(s);
paint(c);
}
static void paint(Shape s1) {
s1.draw();
}
}
|
At the runtime, the paint method takes a variable of Shape type and the draw method is called
accordingly.
Overloading method is a kind of prototype pattern too.
Painting.java
class Painting {
public void draw(Point p, int x, int y) {
}
public void draw(Point p, int x) {
}
}
|
To draw the related shape the draw method is called on the bases of the parameters
passed to it.
|
Del.icio.us
Digg
Google
Spurl
Blink
Furl
Simpy
Y! MyWeb
Current Comments
0 comments so far (post your own) View All Comments Latest 10 Comments: