Скачать или смотреть Solving the Value Not Updating Issue in Jetpack Compose Animations

Learn how to effectively update values and create smooth animations in Jetpack Compose, tackling the common issue of values not updating during re-composition.
---
This video is based on the question https://stackoverflow.com/q/67559208/ asked by the user 'Code Poet' ( https://stackoverflow.com/u/5513788/ ) and on the answer https://stackoverflow.com/a/67560207/ provided by the user 'Santanu Sur' ( https://stackoverflow.com/u/7258332/ ) 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: value not updating (Jetpack Compose)

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.
---
Solving the Value Not Updating Issue in Jetpack Compose Animations

If you're working with Jetpack Compose and diving into animations, you might run into a frustrating issue: values that just don’t seem to update correctly when you expect them to. This often leads to animations that don't behave as intended, preventing your app's user interface from functioning smoothly. In this guide, we'll explore a common scenario involving delays in animations and understand how to resolve the value not updating problem.

Understanding the Problem

In Jetpack Compose, every time a state value is changed, the entire composable function is re-composed. This behavior is useful but can sometimes complicate things—especially when trying to manage animations with dynamic delay values. A user reported issues when attempting to animate a list of colored boxes, each with a delay of 1 second after the other. The core of the issue stemmed from how the delay was being managed in the code.

The Code Snippet

Here's an excerpt of the original code that triggered the update issue:

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

The problematic line here was the use of mutableStateOf for the delay. As the delay value was changed within the loop, it caused the entire composable to recompose, and the animation timing would be disrupted.

Solution to the Issue

Instead of using a mutableState for the delay, we can simplify the code by declaring the delay as a simple Int variable. This will allow us to update its value without triggering unnecessary recompositions. Here's a structured solution approach:

Step 1: Use a Basic Integer for Delay

Replace the mutableState for the delay with a straightforward integer. You will then increment this integer within your loop.

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

Step 2: Create Modifier with Animation

Create a function to encapsulate your animation logic. This can address both the X and Y position based on the animation state.

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

Step 3: Update Animation Logic

Create a function for handling animations. This will take care of your transition logic without unwanted recompositions.

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

Now update your forEachIndexed logic as follows:

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

Conclusion

By utilizing a standard integer variable for delay and creating specific functions to handle modifiers and animations, you can effectively circumvent the issue of value not updating. This allows you to create a seamless animation experience in your Jetpack Compose application. If you face issues like this in the future, remember that how you manage state can greatly affect performance and functionality. Happy coding!