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How setState() function redraw the new state after quick changes in statefull management in Flutter

It easily redraw the new state but how this concept work?
I am beginner in Flutter

2

Answers


  1. According to Flutter Documentation,

    Calling setState notifies the framework that the internal state of
    this object has changed in a way that might impact the user interface
    in this subtree, which causes the framework to schedule a build for
    this State object.

    So if you want to update the state of a widget then you need to use a setState function. Though you must have a Stateful Widget in order to use it as a widget’s state can’t be changed in a Stateless Widget. You can read more about it on Flutter Website

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  2. Statefull widgets are obvious in flutter, these widgets are immutable but their states are mutable, they can change,

    https://api.flutter.dev/flutter/widgets/StatefulWidget-class.html

    When you finally run your APP, you create a widget tree and for that widget tree flutter creates a corresponding element tree,

    So when you call setState, the flutter framework checks for changes in widget tree and and updates corresponding element tree,

    ****Flutter framework is so smart that without building whole element tree from the scratch, it just updates it as per changes in widget tree.

    ***To get more performance benefit keep the state deeper inside the widget tree so the parents remain unaffected while flutter framework update the element tree.

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