Resolving NoSuchMethodError: The getter was called on null in Flutter Localization

Learn how to fix the `NoSuchMethodError` when dealing with Localization in Flutter, specifically in the BottomNavigationBar. Follow our step-by-step guide to streamline your app's language handling.
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An Insight into Flutter Localization Errors: Understanding and Solving NoSuchMethodError

In the world of Flutter development, localization is a powerful feature that allows you to serve diverse users by translating your app to their native languages. However, while implementing this feature, you may encounter the NoSuchMethodError: The getter was called on null. This particular error arises due to an inadvertent misconfiguration in your code, particularly with the improper use of MaterialApp. In this guide, we will explore the problem in detail and provide a clear solution to ensure your BottomNavigationBar reflects the intended localization changes.

Problem Overview

You may have successfully changed the AppBar title language, but when it comes to the BottomNavigationBar, you might see the following error message:

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

This error usually means there was an attempt to access a property of an object that is null. In your case, this happens when trying to use the localization in the BottomNavigationBar. Let's break down why this occurs.

Analyzing the Code Structure

Upon inspecting your code, the issue arises because you have defined two MaterialApp widgets in your widget tree. Here’s a snapshot of the relevant parts of your code:

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

And again, you have another MaterialApp in your _MyAppState:

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

Having multiple MaterialApps can lead to scoping issues. Specifically, the localization context is lost for your BottomNavigationBar which leads to the error message you have encountered.

Solution: Refactoring Your Code Structure

To solve this problem, you only need one MaterialApp. This means you’ll need to remove the second instance from the _MyAppState class. Follow these steps to fix the issue:

Step 1: Retain Only One MaterialApp

Remove the MaterialApp inside _MyAppState: Since you already have one in MainPage, there's no need for another.

Use scaffold directly in the MainPage's MaterialApp.

Step 2: Update the Widget Tree

Here’s how the corrected structure should look like:

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

Step 3: Update the bottomNavigationBar

The BottomNavigationBar items should now correctly access localized strings, since they will inherit the correct context.

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

Conclusion

By making these changes to streamline your app's structure, you should be able to resolve the NoSuchMethodError and properly localize your BottomNavigationBar. Remember, localization is crucial in enhancing the user experience, and keeping your widget tree clean will facilitate easier debugging and better performance.

With careful handling of widget context, you can ensure all parts of your app reflect the user's preferred language, thereby making your Flutter application more inclusive and user-friendly. Happy coding!