Activity life cycle diagram in detail

Definition:

The Activity Life Cycle is the order of stages that an Android Activity passes through from being created to being destroyed. It is powered by Android OS that is controlled via pre-defined lifecycle callback methods including onCreate, onStart, onResume, onPause, onStop and onDestroy.

Introduction

An Activity is a single, focused thing that the user can do in android app. As mobile apps are typically executed within a dynamic environment with resource constraints, the system can create, suspend, resume or destroy Activities any time. So that you can manage these transitions page-style, Android provides a very clearly defined Activity Life Cycle. Knowing this life cycle is crucial in developing a stable, responsive and user-friendly apps.

Explanation

The Activity Life Cycle has several states and each state corresponds to a callback method. User actions, system events, and screen orientation changes can switch between these states. The primary life cycle methods are:

onCreate()

This is the first call when an Activity is created. it just inits UIs, loads layouts, binds data and load needed resources.

onStart()

Called when the activity is becoming visible to the user, but is not yet ready for the user to interact with. Some key UI prep can happen here.

onResume()

The Activity comes into the foreground and is interacted with. This is where you typically start animations, sensors and listeners.

onPause()

onPause(): This method gets invoked when another Activity partially covers the current one. The Activity’s UI is still displayed, but not in the foreground. Temporary modifications, for example saving unsaved data, pausing animations is done here.

onStop()

The Activity is not visible to the user. Any heavy resources like the network calls, or the broadcast receivers must be released here.

onRestart()

Invoked when the Activity goes back or returns from a stopped sate to an active state. It happens once the user goes back to your Activity.

onDestroy()

The last method called before the Activity is destroyed. Here is where cleanup, such as closing database connection or releasing a resource occurs.

Diagram Flow (Textual):

onCreate() → onStart() → onResume() → [Activity Running] → onPause()click here for image→ onStop() (if another activity is, as an example, on top of this one) → onDestroy()(Note: onPause will always be called before the destruction of any Activity.

Or, if they have returned to the Activity:

onStop() → onRestart() → onStart() → onResume()

Features / Characteristics

Gives the expected control over what Activity does.
Aids in efficient memory handling in a mobile setting.
Provides menu and UI transition smooth as butter.
Provides callbacks for saving and restoring UI state.
Manages interruptions such as phone calls, notifications and switching apps.
Handles configuration changes, such as orientation or language.
Allows to manage resources correctly and prevent memory leaks.

Example

Let’s imagine an Activity that would play a video:
onCreate(): Video player UI is laid out and resources are set up.
onStart(): Video preview is prepared.
onResume(): Video playback starts.
onPause(): When a call arrives, playback is suspended.
onStop(): When the Activity is destroyed, video is shutdown.
onDestroy(): Player resources are released to reclaim memory.

This specimen demonstrates how life cycle methods are used to handle app activity through real-time events.

Advantages / Importance

Helps maintain application stability.
Keep user experience smooth between changes.
Prevents the app from crashing when interrupted.
Predictable and consistent state management.
Prevents memory leaks by freeing up the resources that aren’t used anymore.
It’s Android, so it can button multitask and run in the background.

Necessary for apps which use the media, sensors and running in background features.

Conclusion

The Activity Life Cycle is a core concept for Android development. Once you’ve comprehended each state and its callback methods, app development becomes faster, more responsive and more stable. It guarantees the correct use of resources, seamless interactions and solid response to system driven changes – it’s a very interesting issue in mobile app development.

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