Mutable vs immutable objects

Question

I\'m trying to get my head around mutable vs immutable objects. Using mutable objects gets a lot of bad press (e.g. returning an array of strings from a method) but I\'m hav

Answer 1

Mutable collections are in general faster than their immutable counterparts when used for in-place operations.

However, mutability comes at a cost: you need to be much more careful sharing them between different parts of your program.

It is easy to create bugs where a shared mutable collection is updated unexpectedly, forcing you to hunt down which line in a large codebase is performing the unwanted update.

A common approach is to use mutable collections locally within a function or private to a class where there is a performance bottleneck, but to use immutable collections elsewhere where speed is less of a concern.

That gives you the high performance of mutable collections where it matters most, while not sacrificing the safety that immutable collections give you throughout the bulk of your application logic.