Impact of changes on singleton class loaded by different classloaders

Question

If i have multiple instances of singleton class on different class loaders
and if i have modifications to a reference variable in any of these instances.

E.g if i add/remove an element to Hashmap

Does the change/modification impact the instances on other class loaders as well?

Answer 1

Singleton is per classloader. so changes wont impact other instances loaded using other classloaders.

there are couple of good references:

• on Singleton and different classloaders
• on Static members and different classloaders

Answer 2

Your "singleton" is one instance per JVM.

Here is a good article discussing classloaders, the relationship between different classloaders to each other, and to the JVM:

http://javapapers.com/core-java/java-class-loader/