Android Activity & Fragment Lifecycle

In Android development, Activities and Fragments are essential components that help create engaging user interfaces. Understanding their roles and lifecycles is crucial for building responsive and user-friendly applications.

What is an Activity in Android?

An Activity is a key Android app component, representing a single screen where users can interact with content. It is fundamental to the user experience and has a defined lifecycle.

Lifecycle:

• An activity progresses through various states: created, started, resumed, paused, stopped, and destroyed. It is managed using lifecycle methods, which are crucial for responding to user actions and system events.

User Interaction:

• Activities handle user actions, such as tapping buttons or entering text, updating the UI based on these interactions.

Navigation:

• Activities are linked using intents, allowing users to move between different screens in the app.

UI Composition:

• The layout is defined using XML files or Jetpack Compose, determining the appearance and elements on the screen.

What is a Fragment in Android?

A Fragment is a modular component that represents a portion of the user interface in your Android app. It allows for flexible and dynamic layouts, enhancing the user experience.

Lifecycle:

• Fragments have their own lifecycle stages: created, started, resumed, paused, stopped, and destroyed. They are managed through methods like onCreateView(), onViewCreated() and onDestroyView(), which are essential for ensuring proper functionality.

Modularity:

• Fragments enable you to break your UI into smaller, reusable components, allowing for flexible layouts that adapt to various screen sizes.

User Interaction:

They respond to user actions like button clicks, updating the UI accordingly, and can be displayed simultaneously for a richer experience.

Navigation:

• Fragments can be replaced or added within an activity using Fragment Transactions, facilitating seamless transitions.

Communication:

• Fragments can communicate with their host activity or other fragments using interfaces or shared ViewModels.

Understanding Activities and Fragments is crucial for any Android developer. By mastering these components, you can create robust, dynamic applications that provide an excellent user experience.