Скачать или смотреть How to Save ViewModel State in Android When Rotating the Screen

Learn the updated method to save the ViewModel state in your Android application during screen rotation to prevent data loss.
---
This video is based on the question https://stackoverflow.com/q/65432234/ asked by the user 'Doragon' ( https://stackoverflow.com/u/14481140/ ) and on the answer https://stackoverflow.com/a/65432269/ provided by the user 'Sam Chen' ( https://stackoverflow.com/u/3466808/ ) 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: Save ViewModel when turning screen android

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.
---
Mastering ViewModel State Management in Android: Essential Steps to Save State During Screen Rotation

As an Android developer, one of the common challenges you may face is how to efficiently manage your app's state during configuration changes such as screen rotations. This is particularly crucial when dealing with ViewModels as losing their state can lead to a frustrating user experience. In this guide, we will address a common question regarding this issue and provide an updated solution to ensure your app maintains its state seamlessly even when the screen is rotated.

The Problem: Managing ViewModel During Screen Rotation

When working with ViewModels in Android, the concept of saving state becomes significant, especially when users rotate their devices. If you've followed guides or older guides, you might have encountered the following code snippet used to obtain a ViewModel:

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

However, if you have noticed that ViewModelProviders.of is marked with a strikethrough, it indicates that this method is deprecated and, therefore, not recommended for use in current Android development. This raises the question: What's the current best practice for handling ViewModel state during configuration changes? Let’s dive into the solution.

The Solution: Using the Updated ViewModelProvider

To handle ViewModel states properly in the latest versions of Android, you should utilize the updated ViewModelProvider method. Here’s how you can implement it effectively:

Step-by-Step Implementation

Import the Necessary Libraries: Ensure you have the required libraries added in your build.gradle file, particularly the lifecycle and ViewModel dependencies.

Modify Your ViewModel Retrieval Code: Update your ViewModel handling logic using the new approach as follows:

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

Logging for Verification: Continue to log the retrieval of your ViewModel to ensure it's properly instantiated without any issues. You can maintain your previous logging statement:

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

Why This Works

The ViewModelProvider class is designed to handle the lifecycle of ViewModels in a more modern way, automatically managing their states during various configuration changes. By using this approach, your ViewModel will persist its data even when the activity or fragment is recreated during events like screen rotation.

Additional Tips for Managing State

Use LiveData: Pair your ViewModel with LiveData to easily observe data changes in the lifecycle-aware manner. This will help keep your UI in sync with the underlying data.

Testing: Always test your application through various states, including rotation, to confirm that the ViewModel is maintaining its data as expected.

Conclusion

Handling ViewModel states during screen rotations in Android doesn't have to be complicated. By adopting the updated ViewModelProvider method, you can ensure your app preserves data integrity and provides a seamless user experience. This way, your users will appreciate the fluidity of your app without dealing with lost inputs or reset states.

By following these steps, you'll be on your way to mastering state management in Android, making your applications more robust and user-friendly. Happy coding!