What is Activity in Android?

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Activity is like a frame or window in java that represents GUI. It represents one screen of android.

In Android, an “activity” is a fundamental component of the Android application architecture. It represents a single screen with a user interface, and it is a crucial building block for creating interactive applications. Each activity is usually defined as a Java class and corresponds to a specific task or user interaction.

Key characteristics of an Android activity include:

  1. User Interface (UI): An activity typically presents a UI to the user, which can include various widgets like buttons, text fields, images, etc.
  2. Lifecycle Management: Activities have a well-defined lifecycle, which includes methods like onCreate(), onStart(), onResume(), onPause(), onStop(), and onDestroy(). These methods allow developers to manage the state and behavior of the activity throughout its existence.
  3. Intent Handling: Activities are often started and communicated with using intents. Intents are messages that allow the components of an application to request functionality from other components, including activities.
  4. Task and Back Stack: Activities are managed in a task, and the Android system maintains a back stack of activities. When a new activity is started, it is pushed onto the stack. The user can navigate back through the stack by pressing the back button.

Here’s a simple example of an activity in Android:

java
public class MainActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);// Your initialization and UI setup code goes here
}
}

In this example, MainActivity is an activity that sets its content view to a layout defined in the activity_main.xml file and performs any necessary initialization in the onCreate method.