Activity lifecycle methods (onCreate, onStart, onResume, onPause, onStop, onDestroy) in Android Kotlin - UI Render Trace

Component - Activity lifecycle methods (onCreate, onStart, onResume, onPause, onStop, onDestroy)

This component shows the Android Activity lifecycle methods. These methods run at different times as the app screen (Activity) opens, becomes visible, gains focus, loses focus, stops, or is destroyed. They help manage what the app does during these changes.

Widget Tree

ActivityLifecycleDemo
├── onCreate()
├── onStart()
├── onResume()
├── onPause()
├── onStop()
└── onDestroy()

The ActivityLifecycleDemo is the main screen. It has six lifecycle methods as its key parts. Each method runs in order as the Activity moves through states: creation, becoming visible, gaining focus, losing focus, stopping, and destruction.

Render Trace - 6 Steps

Step 1: ActivityLifecycleDemo

Step 2: ActivityLifecycleDemo

Step 3: ActivityLifecycleDemo

Step 4: ActivityLifecycleDemo

Step 5: ActivityLifecycleDemo

Step 6: ActivityLifecycleDemo

State Change - Re-render

Trigger:User presses home button or switches to another app

Before

Activity is running and visible (onResume state)

→

After

Activity moves to background (onPause then onStop called)

Re-renders:The Activity lifecycle methods onPause and onStop run; UI is no longer visible.

UI Quiz - 3 Questions

Which lifecycle method runs first when the Activity is created?

A onResume

B onCreate

C onStart

D onDestroy

Key Insight

Understanding Activity lifecycle methods helps you manage app behavior during screen changes. For example, you save data in onPause or onStop and release resources in onDestroy. This keeps your app smooth and efficient.