What is key flutter?

Flutter commonly uses keys when it needs to uniquely identify specific widgets within a collection . Using keys also helps Flutter preserve the state of StatefulWidget s while they’re being replaced with other widgets or just moved in the widget tree.

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Why is state in Flutter?

State is information that (1) can be read synchronously when the widget is built and (2) might change during the lifetime of the widget. It is the responsibility of the widget implementer to ensure that the State is promptly notified when such state changes, using State. setState.

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