What is the purpose of the "key" attribute in Flutter?
The "key" attribute in Flutter is used to uniquely identify a widget in the widget tree. Each widget in the tree must have a unique key, which is used by Flutter to efficiently update the UI when changes are made.
The key is an object that Flutter uses to determine whether a widget has been added, removed, or moved within the widget tree. When a widget is added, its key is used to determine where it should be placed in the tree.
When a widget is removed, its key is used to identify which widget should be removed from the tree. When a widget is moved, its key is used to determine its previous location in the tree, so that it can be efficiently updated in its new location.
Keys are especially useful when working with widgets that have state, such as form fields or list items, because they help Flutter to preserve the state of these widgets when they are moved or removed from the tree.
