Understanding Keys in Flutter: GlobalKey, LocalKey, ValueKey and UniqueKey

How to Manage Widget Uniqueness and State in Flutter

Icon by Freepik — Flaticon

In Flutter, keys play a crucial role in managing the identity of widgets within your app. They help Flutter differentiate between widgets, maintain states, and optimize the rendering process.

Whether it’s about uniquely identifying a widget throughout the app or just within a specific part of the UI, different types of keys serve different purposes. This article explores the key differences and uses of GlobalKey, LocalKey, ValueKey, and UniqueKey, helping you understand how and when to use them effectively in your Flutter projects.

GlobalKey

GlobalKey is a kind of key that allows you to uniquely identify a widget across the widget tree. Unlike LocalKeys, which are used for ensuring uniqueness within a specific level of the tree (More on that further down below), GlobalKey provides global access to a widget, making it useful in scenarios where you need to reference a widget outside its immediate parent.

Global keys are especial when you want to access the state of a stateful widget from outside the widget tree. Or you want to maintain a state of a widget even when it moves around in the widget tree. It is also useful when you…