Why define object for getEntry in HashMap

Question

I am new to generics and I am not sure if the answer to my question is opinion based or has a genuine reason. In the following code what was need to case a key

Answer 1

This is an extreme optimization measure that is probably not necessary for general purpose programming practice. Here is a discussion that could answer your question. Below statement is copied from that post:

It's a coding style made popular by Doug Lea. It's an extreme optimization that probably isn't necessary; you can expect the JIT to make the same optimizations. (you can try to check the machine code yourself!) Nevertheless, copying to locals produces the smallest bytecode, and for low-level code it's nice to write code that's a little closer to the machine.