ActivityResult

ActivityResult is a mechanism in Android development used for passing data back from an activity that was launched to perform a task. When one activity starts another for a result, it uses the startActivityForResult method. The launched activity then performs its task, and when it's finished, it can return a result to the original activity. This result typically includes a result code (indicating success or failure) and optionally, some data, often in the form of an Intent. The original activity receives this result in its onActivityResult callback method.

The startActivityForResult method requires a request code, which is an integer that uniquely identifies the request. This request code is crucial for distinguishing between different results when the original activity might have launched multiple activities for results. The launched activity sets the result using setResult, providing the result code and the data Intent. The onActivityResult method in the originating activity receives the same request code, allowing it to match the received result to the correct request.

Common use cases for ActivityResult include picking a photo from the gallery, taking a picture with the camera, selecting a contact, or making a selection from a list. The ActivityResult API provides a structured way for activities to communicate and share information, making it a fundamental part of Android's inter-activity communication. It enables a cleaner separation of concerns, where one activity can delegate a task to another and receive the outcome without needing to know the internal implementation details of the second activity.