Prefer Immutable Objects

Prefer Immutable Objects

Keep model objects immutable and hold changing state, such as which items are checked, separately, because mutating a field may not trigger setState and leaves the UI stale.

Prefer immutable objects to avoid unintended state mutations.
Mutable state might not trigger setState, leading to incorrect UI rendering.

Instead of using mutable fields (e.g., bool checked in an Item class), represent state separately, such as:

List<Item> items;
List<Item> checkedItems;

This makes it easier to add additional states for the screen,
while keeping the model Item consistent across different parts of the app.