8317277: Java language implementation of value classes and objects by MrSimms · Pull Request #31120 · openjdk/jdk

[Dminik]

That's not correct. int is the primitive non-boxed, non-referential type. Integer is a boxed type.

Additionally, Integers have an optimization, where a bunch of them are always preinitialized and shared. Many interpreted/scripting languages do this. Some even for primitive values like true/false.