Скачать или смотреть How to Fix the Closure Call with Mismatched Arguments Error in Flutter

Learn how to solve the `Closure call with mismatched arguments` error in Flutter apps, especially when dealing with callback functions and button interactions.
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Understanding the Closure Call with Mismatched Arguments Error in Flutter

If you're a Flutter developer, you might have encountered the error message: Closure call with mismatched arguments: function '_MyAppState.build.<anonymous closure>' when interacting with buttons in your app. This problem can be particularly frustrating for those who are just starting out with Flutter, especially if you're working through an older guide. In this guide, we'll explore what causes this error and how to fix it effectively.

The Problem Explained

This error typically arises when there is a mismatch between the expected parameters of a closure (a function or code block that can be passed around) and the actual parameters provided during a function call. This situation commonly occurs in callbacks, especially when you're trying to pass values to a function in a Flutter application.

Example Scenario

In the context of a Flutter quiz app, you might be dynamically generating a list of answer buttons based on quiz questions and responses. Here’s a simplified snippet that represents the issue:

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

In this example, antwortFrage is designed to take an integer argument (the score associated with each answer) but might be incorrectly referenced in your code, which leads to the aforementioned error.

The Solution

After debugging the issue, it was determined that the error stemmed from a null exception handler within the Flutter SDK. Here, we break down the steps you can take to resolve this error effectively:

Step 1: Downgrade the Flutter SDK (if necessary)

If you are using a newer version of Flutter, try downgrading to version 2.11.0 by updating your pubspec.yaml file. This specific version may resolve compatibility issues that can lead to the error.

Step 2: Modify the Function Signature

Another solution is to adjust the function signature in your antworten.dart file. Here’s how you can rewrite the Antwort class:

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

By modifying the function declaration in this way, you can ensure that the auswahlVerarbeitung parameter can accept a wider range of callback signatures without throwing an error.

Summary of Changes

To recap, here are the key steps to fix the Closure call with mismatched arguments error in your Flutter app:

Downgrade the Flutter SDK to version 2.11.0, if you’re facing compatibility issues.

Remove parentheses from your Function type declaration in antworten.dart to avoid improper type mismatch.

Ensure Proper Type Casting for any parameters expected by your closures to match their function signature accurately.

By following these guidelines, you should be able to eliminate the error and ensure that your Flutter app's buttons function correctly. Implement these changes and test your application to see if the issue persists.

Conclusion

Errors like Closure call with mismatched arguments can be daunting, especially for those new to Flutter development. By understanding the underlying issues and implementing the outlined solutions, you can enhance your troubleshooting skills and improve your programming experience. Keep persevering, and soon you'll be developing complex applications with ease!