Скачать или смотреть Solving InstantiationException in Kotlin Android: No Zero Argument Constructor Found

Encountering `InstantiationException` due to missing zero argument constructor in Kotlin Android? Learn how to fix it efficiently!
---
This video is based on the question https://stackoverflow.com/q/67084124/ asked by the user 'Amit Sharma' ( https://stackoverflow.com/u/5957968/ ) and on the answer https://stackoverflow.com/a/67084793/ provided by the user 'zhangxaochen' ( https://stackoverflow.com/u/1150712/ ) 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: java.lang.InstantiationException: java.lang.Class com.example.exampleproject.ExampleActivity has no zero argument constructor

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.
---
Understanding InstantiationException in Kotlin Android

When developing applications in Kotlin for Android, you might run into various exceptions that can halt your progress. One such common issue is the InstantiationException, which indicates that a class does not have a zero-argument constructor. In this guide, we’ll tackle this specific problem that many new developers face and provide a practical solution.

What is the Problem?

You may have encountered the following error message while running your app:

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

This error occurs because Android requires an activity class (in this case, LoginActivity) to be instantiated without passing any parameters, which can be the case during the creation of instances when the app runs.

Why Does This Happen?

In Kotlin, when you define a class with a primary constructor that has parameters, the default no-argument constructor is not available unless explicitly defined. Because of this, when the Android framework attempts to create an instance of your activity, it fails to find a suitable constructor, resulting in the InstantiationException error.

How to Fix the Issue

To resolve this issue, you need to modify your activity class to ensure that it can be instantiated without parameters. Below are the steps to address this problem effectively.

Step 1: Modify the Constructor

You need to change your LoginActivity class by removing the constructor parameter. Replace your existing LoginActivity class definition with the following:

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

Key Changes Explained

Constructor Removed: Notice that we've removed the constructor with parameters val ViewModelProvider: Any. This allows the LoginActivity to have a zero-argument constructor, which the Android framework requires.

Inheritance from AppCompatActivity: The activity still inherits from AppCompatActivity, allowing it to utilize the rich features of the Android framework.

Conclusion

By following the simple modification of removing the constructor parameters in your activity class, you allow your Android application to instantiate the necessary class without issues. Make sure every activity you create in Kotlin follows this pattern to avoid facing InstantiationException errors.

Additional Tips

Always ensure that your activities have default constructors to avoid instantiation issues, especially when working with frameworks that instantiate classes dynamically.

Review Android documentation on activities and lifecycles for deeper knowledge about how Android handles activity instantiation.

With these adjustments, you should be on your way to creating a smooth, error-free Android application development experience. Happy coding!