Скачать или смотреть How to Change Widget Variables in Flutter from Another Widget

Learn how to effectively change the state of a Stateful Widget in Flutter. This guide provides clear instructions on using Global Keys to control multiple widgets from a central action.
---
This video is based on the question https://stackoverflow.com/q/62732983/ asked by the user 'wolfeweeks' ( https://stackoverflow.com/u/12223536/ ) and on the answer https://stackoverflow.com/a/62733467/ provided by the user 'Niteesh' ( https://stackoverflow.com/u/13241651/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: Dart/Flutter Trying to change variable of widget from another widget

Also, Content (except music) licensed under CC BY-SA https://meta.stackexchange.com/help/l...
The original Question post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license, and the original Answer post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license.

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
Flutter Tip: Change Widget Variables from Another Widget

If you've been working with Flutter, you may have encountered situations where you want to update or control the state of a widget from another widget. This can be especially challenging if you're dealing with StatefulWidgets. In this post, we’re going to explore a solution to this common problem by demonstrating how to effectively change the variable of one widget from another.

The Challenge: Controlling a Stateful Widget

Let's consider a scenario where you have multiple dice represented as Die widgets, and you want to roll all the dice simultaneously by tapping a button. Typically, each Die has its own state (for instance, the number it displays), but how can we trigger the roll() function of each Die from your Home widget?

Here’s a simplified version of the initial setup:

Die Widget

The Die class is a StatefulWidget that rolls a number between 1 and 6:

[[See Video to Reveal this Text or Code Snippet]]

Home Widget

Your Home widget contains multiple instances of Die and a button to roll them:

[[See Video to Reveal this Text or Code Snippet]]

The Solution: Using Global Keys

The key to solving this problem is the use of Global Keys. Global Keys allow you to access the State of a widget from anywhere in your app, making it easy to control multiple Die instances directly from the Home widget.

Implementation Steps

Define Global Keys: Create a GlobalKey for each die you want to control.

Assign Keys to Dice: When instantiating each Die, assign it its corresponding GlobalKey.

Call Roll Method: Within the onTap method of your GestureDetector, call the roll() method of each Die through its Global Key.

Here’s how your modified Home class would look:

[[See Video to Reveal this Text or Code Snippet]]

Conclusion

By utilizing Global Keys, you can effectively manage the state of multiple StatefulWidgets from a central widget. This method not only simplifies your code but also enhances its readability and maintainability. With this approach, you can now create engaging and interactive Flutter applications with ease! Happy coding!