Activity Lifecycle In Android:

Table Of Content

1. Activity Lifecycle In Android:
2. Activity Lifecycle Example In Android Studio:
3. Output:

Activity Lifecycle In Android:

As mentioned earlier, activities are the foundations upon which you build screens for your app. They encompass multiple components the user can interact with, and it’s likely that your app will have multiple activities to handle the various screens you create.

Having all these activities doing different things makes it sound like developing an Android app is a complicated undertaking.

Fortunately, Android handles this with specific callback methods that initiate code only when it’s needed. This system is known as the activity lifecycle.

Handling the various lifecycle stages of your activities is crucial to creating a robust and reliable app. The lifecycle of an activity is best illustrated as a step pyramid of different stages linked by the core callback methods:

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Following the diagram above, you can picture the lifecycle in action as it courses through your code. Take a closer look at each of the callbacks:

• onCreate(): Called by the OS when the activity is first created. This is where you initialize any UI elements or data objects. You also have the savedInstanceState of the activity that contains its previously saved state, and you can use it to recreate that state.

• onStart(): Just before presenting the user with an activity, this method is called. It’s always followed by onResume(). In here, you generally should start UI animations, audio based content or anything else that requires the activity’s contents to be on screen.

• onResume(): As an activity enters the foreground, this method is called. Here you have a good place to restart animations, update UI elements, restart camera previews, resume audio/video playback or initialize any components that you release during onPause().

• onPause(): This method is called before sliding into the background. Here you should stop any visuals or audio associated with the activity such as UI animations, music playback or the camera. This method is followed by onResume() if the activity returns to the foreground or by onStop() if it becomes hidden.

• onStop(): This method is called right after onPause(), when the activity is no longer visible to the user, and it’s a good place to save data that you want to commit to the disk. It’s followed by either onRestart(), if this activity is coming back to the foreground, or onDestroy() if it’s being released from memory.

• onRestart(): Called after stopping an activity, but just before starting it again. It’s always followed by onStart().

• onDestroy(): This is the final callback you’ll receive from the OS before the activity is destroyed. You can trigger an activity’s desctruction by calling finish(), or it can be triggered by the system when the system needs to recoup memory. If your activity includes any background threads or other long-running resources, destruction could lead to a memory leak if they’re not released, so you need to remember to stop these processes here as well.

Fragment Example In Android Studio:

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Step 1: Create a new project and name it ActivityApplication

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Step 2: File-> New-> Activity -> Empty Activity following code:

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Step 3: Open activity_main.xml and MainActivity.kt following code:

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Step 4: Open activity_main2.xml and MainActivity2.kt following code:

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Step 5: Run and Output

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