Java Design Pattern: Prototype

Prototype design pattern is used when very similar objects are frequently created. Prototype pattern clones objects and set the changed feature. In this way, less resources are consumed.

1. Prototype Pattern Class Diagram


2. Prototype Pattern Java Example

package designpatterns.prototype;
interface Prototype {
    void setSize(int x);
    void printSize();
// a concrete class
class A implements Prototype, Cloneable {
    private int size;
    public A(int x) {
        this.size = x;
    public void setSize(int x) {
        this.size = x;
    public void printSize() {
        System.out.println("Size: " + size);
    public A clone() throws CloneNotSupportedException {
        return (A) super.clone();
//when we need a large number of similar objects
public class PrototypeTest {
    public static void main(String args[]) throws CloneNotSupportedException {
        A a = new A(1);
        for (int i = 2; i < 10; i++) {
            Prototype temp = a.clone();

3. Prototype Design Pattern Used in Java Standard Library

java.lang.Object - clone()

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