How are internal data structures implemented in MutableList and ImmutableList classes?

In Android, the classes MutableList and ImmutableList differ in their ability to modify contents and internal data structures.

• MutableList is a mutable list, typically implemented based on a dynamic array (e.g., ArrayList). It allows adding, removing, and modifying elements. Internally, it stores elements in an array that can be expanded when necessary.

• ImmutableList is an immutable list, which does not allow changing its contents after creation. In Android and Kotlin, such lists are often implemented as wrappers over regular collections that do not provide modification methods, or as specialized structures optimized for immutability (e.g., persistent data structures). This ensures thread safety and predictable behavior.

Thus, the main difference is that MutableList stores data in a mutable structure (array), while ImmutableList uses a structure that does not allow modification after creation.