Is it a bad practice to add elements to List using getter method in java?

Question

Suppose I have a private ArrayList or a LinkedList inside a class, that I will never assign new reference to it, or in other words this will never

Answer 1

In general, you should not assume that the list being returned by the getter is the original one. It could be decorated or proxied for example. If you want to prevent that a new list is set on the target object, you could define an add method on the target class instead.