π± Android Studio β Full Story Style Notes
Unit 1: Concepts of Android & Setup
1. What is Android?
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Android = Operating System (like Windows for PC, but for mobiles).
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Open-source β free for anyone to use or modify.
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Developed by Google.
πΉ Example: Just like your bike needs an engine to run, your mobile needs Android to run apps.
2. Features of Android
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Open-source β anyone can create apps.
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Connectivity β WiFi, Bluetooth, hotspot.
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Multi-tasking β play music + chat.
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Variety of Apps β Games, Banking, Shopping.
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Notifications β WhatsApp popups, Email alerts.
πΉ Example: Your phone is like a supermarket β you can have many different stalls (apps) working together.
3. Android Architecture (Think of it as a layered cake π)
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Linux Kernel (Base layer) β Controls hardware (camera, battery, WiFi).
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Libraries β Pre-made code for features (database, web, graphics).
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Android Runtime (DVM/ART) β Converts code into something the mobile understands.
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Application Framework β Provides services to apps (manages activities, resources).
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Applications β End-user apps like WhatsApp, Instagram.
4. Dalvik Virtual Machine (DVM)
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Special βmini-computerβ that runs Android apps in small memory.
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Optimized for mobiles (low RAM, small battery).
5. Android Emulator & AVD
πΉ Example: Think of emulator as βacting like a phoneβ inside your computer, so you can test your app without buying a new device.
Unit 2: Creating Basic App
1. Activity
2. Layout
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How things look on the screen β buttons, images, text fields.
πΉ Example: Arranging sofa, TV, and chairs in your living room = layout.
3. AndroidManifest.xml
4. R.java
Unit 3: XML (Extensible Markup Language)
πΉ Example:
Shows a button on screen.
πΉ Example: Think of XML as the blueprint of a house β it doesnβt build the house, but tells workers how it should look.
Unit 4: Android Widgets (UI Basics)
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Title bar β Can hide it for fullscreen apps (like YouTube).
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Orientation β Portrait (vertical) / Landscape (horizontal).
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Button & onClick Event β Tap to do something.
πΉ Example: WhatsApp βSendβ button sends your text.
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Toast β Small popup messages.
πΉ Example: βMessage deletedβ or βCopied to clipboard.β
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ToggleButton β Switch ON/OFF.
πΉ Example: WiFi switch in settings.
Unit 5: Other Widgets (UI Advanced)
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CheckBox β Select multiple things.
πΉ Example: Pizza order β Cheese + Olives + Corn.
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RadioButton β Choose one option only.
πΉ Example: Payment β UPI OR Card OR Cash.
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Spinner (Dropdown) β Select from list.
πΉ Example: Select your city (Surat, Mumbai, Delhi).
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AlertDialog β Popup asking confirmation.
πΉ Example: βAre you sure you want to exit?β
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AutoCompleteTextView β Suggests while typing.
πΉ Example: Google search bar.
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TextWatcher β Watches text changes.
πΉ Example: OTP auto-verifies when you type last digit.
π― Memory Hacks
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Activity = Screen (like different WhatsApp screens)
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Layout = Arrangement (like arranging chairs in a room)
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Manifest = Aadhaar card of app
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Toast = Popup message
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CheckBox = Multi-choice pizza toppings
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RadioButton = One-choice payment method
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Spinner = Dropdown menu
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AutoComplete = Google suggestions
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TextWatcher = OTP auto verify
:::::::IMPORTANT QUESTION ANSWERS ARE AS FOLLOWS::::::
1. What is Android? Write its features and advantages of open-source.
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Android β Open-source OS by Google for mobile devices.
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Features: Multitasking, rich UI, connectivity (WiFi, Bluetooth), app store, security, cloud sync.
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Open-source advantages: Free to use, customizable, huge community support, faster innovation.
2. Explain Android architecture with a neat diagram.
Layers:
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Linux Kernel β hardware drivers.
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Libraries + Android Runtime (ART/DVM) β SQLite, SSL, graphics.
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Application Framework β Activity Manager, Content Providers.
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Applications β SMS, Camera, Contacts, User apps.
(Draw 4 stacked layers in exam.)
3. What is Dalvik Virtual Machine (DVM) / ART? Why is it required?
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DVM: Executes .dex files, optimized for low memory.
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ART (Android Runtime): Uses AOT (Ahead of Time) compilation, better performance.
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Required: Runs Java code on mobile efficiently.
4. Define Activity and explain Activity lifecycle methods.
5. What is Layout? Explain different types with examples.
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Layout = UI structure.
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Types:
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LinearLayout (arrange vertically/horizontally).
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RelativeLayout (position relative to parent/others).
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ConstraintLayout (flexible constraints).
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FrameLayout (stack views).
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TableLayout (rows/columns).
6. Purpose of AndroidManifest.xml with example entries.
7. What is R.java? How does it connect resources to code?
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Auto-generated class β gives unique IDs to resources (layouts, strings, drawables).
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Example: R.layout.activity_main connects XML to Java.
8. What is XML? Write a sample XML layout for Button and TextView.
9. What is a Toast? Write code to display a Toast on button click.
10. Explain ToggleButton with attributes and event methods.
11. Differentiate CheckBox, RadioButton, and ToggleButton with examples.
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CheckBox β Multiple selection (e.g., Pizza toppings).
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RadioButton β Single choice in group (e.g., Gender).
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ToggleButton β Switch ON/OFF (e.g., WiFi).
12. What is Spinner? Write steps/code to implement it.
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Define <Spinner> in XML.
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Create array in strings.xml.
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Use ArrayAdapter.
13. What is AlertDialog? How to create a Yes/No confirmation dialog?
14. Explain AutoCompleteTextView with an example.
15. Explain TextWatcher with a real-life use case (e.g., OTP auto-verify).