Q-1: Attempt the following (5 Marks)

Questions

a) List features of Android Operating System.
b) Define Android Virtual Devices (AVD).
c) List all attributes to develop a simple button.
d) List any four Android Layouts.

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Answers

a) Features of Android Operating System

1. Open Source: Android is based on Linux kernel and is open source
2. Multi-tasking: Supports running multiple applications simultaneously
3. Rich UI: Provides attractive and intuitive user interface
4. Connectivity: Built-in support for WiFi, Bluetooth, 3G, 4G, 5G
5. Storage: Uses SQLite database for data storage
6. Media Support: Supports various audio, video, and image formats
7. Messaging: SMS, MMS, and various messaging applications
8. Web Browser: Built-in web browser based on WebKit engine
9. Java Support: Applications are developed using Java programming language
10. Security: Application sandbox for security
11. Memory Management: Automatic memory management and garbage collection
12. Multi-touch: Support for multi-touch screens

b) Android Virtual Devices (AVD)

Definition: Android Virtual Device (AVD) is an emulator configuration that lets you model an actual device by defining hardware and software options to be emulated by the Android Emulator.

Key Points:

• Purpose: Used for testing Android applications without physical device
• Configuration: Includes system image, hardware profile, and emulator options
• Components:
  • Hardware profile (screen size, resolution, RAM, etc.)
  • System image (Android version, API level)
  • Storage options (SD card, internal storage)
• Creation: Created using AVD Manager in Android Studio
• Benefits:
  • Test on different screen sizes and resolutions
  • Test different Android versions
  • Debug applications easily
  • No need for physical devices during development

c) Attributes to develop a simple button

Common Button Attributes:

1. android:id - Unique identifier for the button
2. android:layout_width - Width of the button (wrap_content, match_parent, specific dp)
3. android:layout_height - Height of the button
4. android:text - Text displayed on the button
5. android:textSize - Size of the text
6. android:textColor - Color of the text
7. android:background - Background color or drawable
8. android:onClick - Method to call when button is clicked
9. android:padding - Internal spacing
10. android:margin - External spacing
11. android:gravity - Text alignment within button
12. android:enabled - Whether button is clickable
13. android:visibility - Visibility of button (visible, invisible, gone)
14. android:drawableLeft/Right/Top/Bottom - Add icons to button

Example:

<Button
    android:id="@+id/myButton"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Click Me"
    android:textSize="16sp"
    android:textColor="#FFFFFF"
    android:background="#2196F3"
    android:onClick="buttonClick" />

d) Four Android Layouts

1. LinearLayout

   • Arranges views in a single row or column
   • Uses orientation attribute (horizontal/vertical)
   • Simple and commonly used layout

2. RelativeLayout

   • Positions views relative to each other or parent
   • Flexible positioning using relative attributes
   • Good for complex layouts with fewer nested views

3. ConstraintLayout

   • Most flexible layout manager
   • Uses constraints to position views
   • Flat view hierarchy for better performance
   • Recommended for complex UIs

4. FrameLayout

   • Simple layout holding single child view
   • Child views are drawn in stack (last added on top)
   • Used for fragments and simple containers

Other Common Layouts:

• TableLayout: Arranges views in rows and columns
• GridLayout: Arranges views in grid format
• CoordinatorLayout: Advanced layout for material design
• ScrollView: Provides scrolling functionality

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