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package com.java;

import java.lang.reflect.Constructor;

// Singleton class

class Singleton {

// public instance initialized when loading the class

public static Singleton instance = new Singleton();

private Singleton() {

// private constructor

}

}

public class SingletonBreakReflectionEx {

public static void main(String[] args) {

Singleton instance1 = Singleton.instance;

Singleton instance2 = null;

try {

Constructor[] constructors =

Singleton.class.getDeclaredConstructors();

for (Constructor constructor : constructors) {

// Below code will destroy the singleton pattern

constructor.setAccessible(true);

instance2 = (Singleton) constructor.newInstance();

break;

}

} catch (Exception e) {

e.printStackTrace();

}

System.out.println("instance1.hashCode():- "

+ instance1.hashCode());

System.out.println("instance2.hashCode():- "

+ instance2.hashCode());

}

//Overcome reflection issue: To overcome issue raised by reflection,

// enums are used because java ensures internally that enum value is instantiated only once.

// Since java Enums are globally accessible, they can be used for singletons.

// Its only drawback is that it is not flexible i.e it does not allow lazy initialization.

public enum SingletonEnum

{

INSTANCE;

}

}