Скачать или смотреть How to Save and Update Values Between Activities in Android Studio

Learn how to properly save and update values between two activities in Android Studio using Kotlin, ensuring your app correctly reflects user edits.
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This video is based on the question https://stackoverflow.com/q/63974099/ asked by the user 'penfew' ( https://stackoverflow.com/u/10773183/ ) and on the answer https://stackoverflow.com/a/63974563/ provided by the user 'Egor' ( https://stackoverflow.com/u/543539/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Introduction

In Android app development, passing data between activities is a common requirement. A frequent challenge arises when developers want to ensure that any edits made in a second activity are reflected in the first activity upon returning. In this guide, we will explore how to fix a common issue encountered while saving updated values between two activities in Android Studio using Kotlin.

The Problem

Imagine you have a main activity displaying a simple text "cat". There is a button that, when pressed, opens a second activity allowing users to edit this text. However, when users go back to the main activity, the text reverts back to "cat", instead of reflecting the changes made by the user. This happens because the value being passed back from the second activity is not being set correctly. Let's discuss where the issue lies and how to resolve it.

Understanding the Code

We will take a closer look at the implementation of both activities involved. Below is an overview of the Main Activity and Second Activity code:

Main Activity Code

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In this code, name is a variable defined within onCreate(), and it will not update after the initial assignment. When the intent is created for the second activity, it always sends the original value of "cat".

Second Activity Code

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

The second activity correctly retrieves the editable name and sends it back when the back button is pressed.

The Solution

To resolve the issue of not retaining user edits, we need to modify how we pass the updated value of the text back to the main activity.

Steps to Fix the Issue:

Change the Intent Data Passing: Instead of using the name variable from onCreate, use the value from the TextView directly when creating the Intent.

Update the Code as Follows: Replace the problematic line in the Main Activity where the Intent is created:

From:

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

To:

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

Final Updated Main Activity Code

Here’s how the Main Activity should look after the changes:

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

Conclusion

By ensuring that we always send the current value of the text, rather than a static variable, we can keep our application state current and provide a better user experience. This approach is essential when dealing with multiple activities in Android development. Now that you know how to save and update values between activities, you can implement this strategy in your own apps! Happy coding!