What is the difference between google's ImmutableList and Collections.unmodifiableList ()?

Question

From ImmutableList javadocs:

Unlike Collections.unmodifiableList(java.util.List), which is a view of a separate collection that can still change

Answer 1

Using Collections.unmodifiableList creates a wrapper around your List. if the underlying list changes, so does your unmodifiableList's view.

As the documentation says, Google's code creates a copy. It's a more expensive computation and consumes more memory, but if someone alters the original list, it cant affect the ImmutableList.

Neither of these will prevent you from changing an object in a list, or it's fields, or fields of fields, etc.