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An Activity is an Android app component that provides an entry point for interaction and a window for the app’s interface. A Fragment is a reusable part of a user interface that must be hosted by an Activity or another Fragment. For a new multi-screen app built with Views, Android guidance commonly favors one Activity hosting Fragment-based navigation; an app built entirely with Compose should use Compose navigation destinations.
What is the difference between an Activity and a Fragment?
They serve different levels of an app’s structure. The Android system manages Activities as app components. A Fragment modularizes interface content within a host; it is not an independent app entry point.
| Decision point | Activity | Fragment |
|---|---|---|
| Role | App component, interaction entry point, and UI window. | Reusable portion of UI hosted by an Activity or another Fragment. |
| Lifecycle ownership | The system drives Activity lifecycle callbacks. | FragmentManager and the parent constrain the Fragment’s state; its view has a separate lifecycle. |
| Navigation | Can launch another Activity, including one in another app, using intents. | Can be a destination in Fragment-based Navigation, or be added, replaced, or removed through transactions. |
| Typical fit | App entry points, windows, and integration with another Activity. | Modular Views screens or screen regions, reusable UI, adaptive layouts, and destinations in a Fragment-based app. |
Android’s Fragments guide describes a Fragment as “a reusable portion of your app’s UI.” A Fragment cannot exist on its own: it needs a host Activity or parent Fragment. An Activity, by contrast, is a system-managed component with its own window and lifecycle.
How do their lifecycles differ?
The system manages an Activity’s lifecycle and calls its lifecycle callbacks as the Activity changes state. A Fragment’s state is managed by FragmentManager and limited by the state of its parent. The Fragment also has a view lifecycle, which is distinct from the lifecycle of the Fragment instance.
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This distinction matters when a Fragment’s view is destroyed while the Fragment instance remains. Bind UI observation and cleanup to the view lifecycle when the work only applies while that view exists. The Fragment lifecycle guide explains the Fragment and view lifecycle states.
Should you use one Activity or multiple Activities?
There is no platform rule requiring every app to use one Activity. However, current Android guidance commonly uses a single host Activity for an app’s navigation, with screen destinations inside it. The right destination type depends on the UI toolkit:
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- Views or a mix of Views and Compose: use Fragment-based Navigation for Views destinations. During an incremental migration from Views to Compose, Android advises continuing with Fragment-based Navigation until the Fragments have been replaced.
- Compose-only app: use Navigation Compose destinations rather than introducing Fragments solely to represent screens.
- App-level entry or external integration: Activities remain appropriate for app entry points, windows, and launching or integrating with another Activity.
See Android’s Navigation documentation and Views architecture recommendations for the current guidance.
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1Clear out junk files and repair common Windows errors2Fix the driver behind crashes, sound loss and screen glitches3Repair Windows errors before they cause bigger problemsWhen should you use a Fragment?
Use a Fragment when a Views-based screen or region benefits from being a distinct, reusable UI module, or when the app needs to add, replace, or remove interface sections within its host. Fragment transactions can also be placed on a back stack. These capabilities can help separate screen content from app-wide navigation and support layouts that adapt to different screen sizes.
Keep Fragments decoupled from one another. Give state to the screen or navigation flow that owns it: an Activity-scoped ViewModel can be broader than necessary for a short multi-step flow in a single-Activity app. Android’s responsive navigation guide covers adapting navigation to different layouts.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Is an Activity or Fragment faster?
The official guidance cited here does not establish that Activities or Fragments are universally faster, nor does it provide a comparative performance statistic. Choose based on component responsibilities, UI toolkit, navigation needs, and modularity rather than an assumed speed advantage.
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