What is the activity lifecycle in Android?

An activity can range from a simple screen with basic controls to a complex layout with multiple fragments and interactions. Activities can be launched individually or can be connected to one another to form a coherent user experience.

Activity lifecycle

The activity lifecycle consists of a series of callback methods that are automatically invoked by the Android system as the activity moves through different stages. These stages include:

• onCreate: This method is called when the activity is first created. It’s where initialization tasks such as setting up the user interface, binding data, and other setup operations take place.

• onStart: This method is called when the activity becomes visible to the user. At this point, the activity is in the foreground, but the user may not yet be interacting with it.

• onResume: This method is called when the activity is about to start interacting with the user. It’s the point at which the activity is active and in the foreground, ready to respond to user input.

• onPause: This method is called when the activity is no longer in the foreground and is partially obscured by another activity or a system event. It’s crucial for releasing resources that aren’t needed when the activity isn’t visible.

• onStop: This method is called when the activity is no longer visible to the user. It occurs when the activity is completely hidden or when another activity comes into the foreground.

• onDestroy: This method is called when the activity is being destroyed. It’s the final stage of the lifecycle and is used for performing cleanup operations and releasing resources held by the activity.

• onRestart: This method is called when the activity is restarting after being stopped. It’s followed by onStart when the activity becomes visible again.

These callback methods allow us to manage the behavior of our application based on the state of the activity. For example, we can save and restore the activity’s state during configuration changes (such as screen rotations) by overriding onSaveInstanceState and using the saved data in onCreate.

Conclusion

Activities are the building blocks of Android applications, enabling developers to create interactive and user-friendly interfaces. Understanding the activity lifecycle is crucial for effectively managing the state and behavior of our app across different scenarios. By properly implementing lifecycle methods and considering use cases, we can create a seamless user experience and ensure that our app responds appropriately to user interactions and system events.