Скачать или смотреть How to Use startActivityForResult in a Class that Extends View

Discover how to effectively use `startActivityForResult` in a custom `View` class by using casting in your Android application.
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This video is based on the question https://stackoverflow.com/q/63100387/ asked by the user 'Тульский Пряник' ( https://stackoverflow.com/u/5080366/ ) and on the answer https://stackoverflow.com/a/63100562/ provided by the user 'Fahima Mokhtari' ( https://stackoverflow.com/u/6651763/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Introduction

When developing Android applications, you often need to start new activities and receive results from them. Typically, this is achieved using the startActivityForResult method in an Activity class, such as one that extends AppCompatActivity. However, what if you want to initiate this process from a class that extends View instead? This post addresses that challenge and provides a clear solution.

The Challenge

You might find yourself in a situation where you are working with a custom view class and want to start another activity and expect a result back from it. In this case, using the method startActivityForResult directly won't work because the View class does not have this method.

Understanding the Problem

Class Extending View: You have a class (ContentsElement) that extends View and includes a button click listener.

Intent to Start New Activity: You're trying to start MainActivity and expect a result.

Method Limitation: The View class does not have direct access to startActivityForResult.

The Solution

To overcome this limitation, you need to cast the Context from your View into an Activity. This allows you to access startActivityForResult. Here’s how you can implement this solution step-by-step:

Step-by-step Solution

Modify Your Code: Locate the line where startActivityForResult is called in your ContentsElement class.

Original code snippet:

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

Cast Context: Change the line to safely cast the context to Activity.

Updated code snippet:

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

Full Updated Code Example

Here's what your complete ContentsElement class will look like after the modification:

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

Conclusion

By casting the Context to an Activity, using startActivityForResult from a custom View class is not only possible but also straightforward. This allows you to maintain a clear structure in your application while also ensuring that interactions with activities are seamless and effective.

Feel free to implement this solution in your own projects as you develop custom views in Android. Happy coding!