Ok will do it suman

But how can we return from the constructor buddy

@@Javatechie Oh ! My bad.

@abhrajitnandy no problem

Will do that

No readResolve only called at the time of deserialize so here we want to return the existing instance . that's why no null check required here

You are correct in lazy Singleton approach we should add null check but if it is eager Singleton approach the Then it's not required . Because on class level we are creating instance in eager loading Singleton approach

@@Javatechie I was pointing to lazy load approach only. Thanks.

That's the reason constructor level itself I added null check

@@Javatechie Can you try this code:- LazySingleton reflectionInstance = null; Class clazz = Class.forName("LazySingleton "); Constructor s3Constructor = clazz.getDeclaredConstructor(); s3Constructor.setAccessible(true); reflectionInstance = s3Constructor.newInstance(); System.out.println("Reflection hashcode :- " + reflectionInstance .hashCode()); LazySingleton instance1 = LazySingleton.getInstance(); System.out.println("Instance hashcode :- " + instance1.hashCode());

@@anirudhjadhav9663 Just saw your comments & I had also same doubt. Tried to solve. Could you please check this below sol if that works. Please let me know if you find any catch here. private static boolean isCallFromMyGetInstance = false; private static MySingletonClass obj; private MySingletonClass(){ if(obj!=null || isCallFromMyGetInstance==false) { throw new IllegalStateException("Object can't be created using reflection for this class"); } } public static MySingletonClass getInstance() { if(obj==null) { synchronized (MySingletonClass.class) { if(obj==null) isCallFromMyGetInstance=true; obj=new MySingletonClass(); } } return obj; }

Serialization never create object . Object can be created using deserialization

@@Javatechie but if objects are not mapped in file then how deserialization will do anything ?

Can we perform deserialization from only file ?

@@Javatechie As per the code you shown a serialization is done in a file. I also have a query that once a class is created which don't extends to myclone and don't implements serelizable interface the how some othe program would be able to make clone out of that class

Let's say your singleton class extends from some other class and that class extends from Serializable then in that situation anyone can deserilize your singleton class right ?

Yes we can

In some worst senario we may need my class to be extends from some other class .so In such case if that class implement Clonable then it will break the rules . So for demonstrate purpose I created this MyClone class

Singleton can't be safe in multiple JVM . Singleton : one instance per JVM

@@Javatechie Thanks for ur response... can u plzz upload end to end spring rest service based app which maintenance user session using basic authentication..

@@satishkumar1799 yeah sure will upload

@@Javatechie Thank You!

Okay I will