Unit 1: Basics of Android OS

UNIT – I : BASICS OF ANDROID OS 

1.1 Introduction to Android Operating System

Q1. What is Android Operating System?

Answer:
Android is an open-source, Linux-based operating system designed primarily for smartphones, tablets, wearables, TVs, and IoT devices. It provides:

  • A Linux kernel for hardware interaction

  • A rich application framework for UI development

  • A runtime environment (Android Runtime, ART)

  • A complete set of libraries for mobile app development

Google leads Android development, but device manufacturers can customize the OS according to their needs.

Q2. Why is Android considered open-source?

Answer:
Android is released under the Apache License 2.0, which allows:

  • Free modification of source code

  • Customization by manufacturers (e.g., Samsung, Xiaomi)

  • Development of custom ROMs

  • Community-driven innovation

This openness makes Android the world’s most widely used mobile OS.

Q3. What makes Android different from traditional operating systems?

Answer:

  • Built specifically for mobile devices

  • Touch-based interface with gestures

  • Battery & resource management optimized for small devices

  • Apps run inside sandbox environments for security

  • Highly customizable UI

  • Supports multiple hardware configurations

1.2 Need and Features of Android

Q4. Why do we need Android in today’s technological world?

Answer:
Android fulfills modern demands such as:

  • A universal platform for mobile computing

  • Support for a large and diverse hardware ecosystem

  • Rapid development of applications using Java/Kotlin or C# (Xamarin)

  • Massive global user base enabling business opportunities

  • Seamless integration with Google services

Its affordability and flexibility make it ideal for both users and developers.

Q5. What are the key features of Android?

Answer:

  1. Open Source Platform
    Free to use, modify, customize.

  2. Customizable User Interface
    OEMs can add their own UI layers (e.g., MIUI, OneUI).

  3. Multi-tasking Support
    Run multiple apps simultaneously.

  4. Supports all Google Services
    Maps, Drive, Gmail, Cloud Messaging.

  5. Adaptive & Responsive UI
    Works across screens: phones, tablets, TVs, watches.

  6. Rich Application Framework
    Activities, Services, Broadcast Receivers, Content Providers.

  7. Connectivity Options
    Bluetooth, Wi-Fi, NFC, USB, GSM, CDMA, VoLTE.

  8. Hardware Support
    Camera, GPS, accelerometer, fingerprint, gyroscope.

  9. Security
    App sandboxing, permissions, Play Protect.

  10. Large Developer Community
    Millions of apps available via Google Play Store.

Connectivity Options (Long Forms):

  • Bluetooth – Wireless technology for short-range communication between devices

  • Wi-Fi – Wireless Fidelity

  • NFC – Near Field Communication

  • USB – Universal Serial Bus

  • GSM – Global System for Mobile Communications

  • CDMA – Code Division Multiple Access

  • VoLTE – Voice over Long-Term Evolution

1.3 Android Architecture Framework

Q6. What is Android Architecture?

Answer:
Android Architecture is a layered structure that organizes the OS components logically to support app development.

It contains four main layers:

Q7. What are the layers of Android Architecture? Explain each.


**1. Linux Kernel Layer

  • Lowest layer

  • Handles drivers (camera, display, Wi-Fi, Bluetooth)

  • Manages processes, memory, and security

  • Acts as hardware abstraction layer for upper layers

**2. Hardware Abstraction Layer (HAL)

  • Provides standard APIs for hardware

  • Developers don’t need to write separate code for each hardware type

  • Bridges hardware and Android Framework

**3. Native Libraries + Android Runtime (ART)

Native Libraries (C/C++)

  • Media Libraries (audio/video playback)

  • Graphics (OpenGL, Skia)

  • SQLite (database)

  • WebKit (web rendering)

Android Runtime (ART)

  • Replaced Dalvik virtual machine

  • Pre-compiles code using AOT (Ahead-of-Time)

  • Faster execution

  • Better memory management

**4. Application Framework

  • Java/Kotlin APIs used by developers

  • Components include:

    • Activity Manager

    • Window Manager

    • Notification Manager

    • Package Manager

    • Telephony Manager

    • Resource Manager

This layer provides the building blocks for app development.

**5. Applications Layer

  • Top layer

  • Includes system apps:

    • Phone, Contacts, Messages

    • Settings

    • Camera

  • Also includes user-installed apps from Play Store

1.4 Introduction to Android Application Development IDEs

Q8. What is an IDE? Why do we use it in Android development?

Answer:
An Integrated Development Environment (IDE) is software that provides tools for writing, testing, debugging, and packaging Android applications.

Benefits include:

  • Code editor with syntax highlighting

  • Emulator support

  • Auto-complete

  • Build tools

  • Debugger

  • Easy integration with SDKs

Q9. What is Android Studio? Explain its features.

Answer:
Android Studio is the official IDE for Android application development, built on JetBrains IntelliJ IDEA.

Key Features:

  1. Intelligent Code Editor (Kotlin, Java)

  2. Layout Editor with drag-and-drop UI design

  3. Gradle-based Build System

  4. Android Virtual Device (AVD) Emulator

  5. Performance Tools

  6. Firebase Integration

  7. Version Control Support (Git)

  8. Instant Run for quick deployment

Android Studio is the most widely used IDE for modern Android apps.

Q10. What is Eclipse? Why is it less used today?

Answer:
Eclipse + ADT (Android Development Tools plugin) was previously used before Android Studio.

Reasons it is less used:

  • Slower performance

  • Lacks integrated tools

  • Difficult configuration

  • ADT plugin discontinued by Google

However, Eclipse is still used for:

  • Legacy projects

  • General Java development

Q11. What is Visual Studio with Xamarin?

Answer:
Xamarin (by Microsoft) allows developing cross-platform apps using C# & .NET.

Features:

  • Build apps for Android, iOS, Windows from a single codebase

  • Uses Xamarin.Android for native Android development

  • Visual designer for UI

  • Seamless integration with Visual Studio

  • Access to native APIs through bindings

Xamarin is preferred for organizations that use the Microsoft ecosystem.

Q12. Compare Android Studio, Eclipse, and Xamarin.

Feature Android Studio Eclipse Visual Studio (Xamarin)
Official Support ✔ Yes ✖ No ✔ Yes (Microsoft)
Language Kotlin/Java Java C#
UI Designer Excellent Limited Good
Build System Gradle ANT/ADT MSBuild
Cross-Platform No No Yes
Performance Fast, optimized Slower Fast


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