This document provides an introduction to Android development. It covers topics such as setting up the development environment, understanding the file system structure, using activities and fragments, handling fragmentation across different devices, and some best practices. The document discusses tools like Android Studio, the build system, and debugging tools. It also explains concepts like the activity lifecycle, saving activity state, targeting different versions and configurations, and using support libraries for backwards compatibility.

1. Android 101
Introduction to Android
Development
Andy Scherzinger
Spare-time Android Dev
AndyScherzinger 28th Jan. 2016

2. Topics
• Dev Setup
• File System Structure
• Activities & Fragments
• Handle Fragmentation
• The little Things

3. Dev Setup
Tool
Chain
Java Language Gradle Build System Android Studio IDE
Android Studio icon CC BY 2.5 Google Inc.

4. Android Studio
Coding Environment & Debugger
SDK Manager
Gradle Integration
Android Device Monitor
Android Virtual Device Manager
Android Studio icon CC BY 2.5 Google Inc.

5. Code to Binary
Java Byte Code Java Byte Code
Java Source Code Java Source Code
Java
Compiler
Java
Compiler
Dalvik Byte Code
Dex
Compiler
Java Byte Code Dalvik Byte Code
Dalvik VM
Android Runtime (ART)
Java VM
https://github.com/devacademy/android-fundamental-one/blob/master/modules/stack.md

6. File System Structure
* Grid, List, UI Partials
• AndroidManifest.xml  your App‘s definition
• build.gradle,…  your build files
• src/java  douh! your implementation
• src/res
– anim  custom animations
– drawable  graphics (pixel, patch9, vector-xml, etc.)
– layout  XML Layouts for Activities, Fragments, *-Items
– menu  XML Menu Files
– raw  any non-specific files
– values  l18n resources, static (array) data, configurations
– xml  Preference Screen, Sync Adapter, etc.

7. Fragment Orchestration
Source: http://developer.android.com/training/basics/fragments/fragment-ui.html
Fragments are UI modules orchestrated via Activities
Fragment
A
Fragment
B
Fragment A Fragment B
Activity 1 Activity 1 Activity 2
Intent

8. Activities & Fragments
– Activity Lifecycle
Source: http://developer.android.com/training/basics/activity-lifecycle/starting.html
Created
Started
(visible)
Resumed
(visible)
Paused
(part. visible)
Stopped
(hidden)
Destroyed
onResume()
onStart()
onStart()
onDestroy()
onStop()
onPause()
onResume()
onRestart()
Android
1
2
3
• (1) Initialize UI
• (2) Checks (e.g. GPS enabled)
• (3) Activity running - Woohoo!
onCreate()

9. Activities & Fragments
– Activity State Save
Source: http://developer.android.com/training/basics/activity-lifecycle/recreating.html
Created Resumed
(visible)
Destroyed
onRestoreInstanceState()
onSaveInstanceState()
Android
2
3
1
• (1) save your state
• (2) / (3) restore the state
onCreate()
Resumed
(visible)

10. Fragmentation
Resolution
& Display Size
Android
Versions
http://opensignal.com/reports/2015/08/android-fragmentation/ - http://developer.android.com/about/dashboards/index.html

11. Target Versions and Sizes
• src/res
– drawable-hdpi-v11
 used for Android 11 and up
– layout-w600dp-land
 used in landscape w/ at least 600dp
width

12. Call Version depending code
• src/java
if (android.os.Build.VERSION.SDK_INT >=
android.os.Build.VERSION_CODES.HONEYCOMB) {
builder.setIconAttribute(android.R.attr.alertDialogIcon);
}…

13. Backwards Compatibility
via Support Lib
• Add libs to build.gradle
dependencies {
compile 'com.android.support:support-v4:23.1.1'
compile 'com.android.support:design:23.1.1'
compile 'com.android.support:appcompat-v7:23.1.1'
}

14. …and hack away…
• UI: AppCompatButton, Drawer, Material Theme,
AppCompatDialog, …
• Functionality: e.g.
ContextCompat.checkSelfPermission
 Android M Permission System Implementation
Backwards Compatibility
via Support Lib

15. The (many) little Things…CodeUIMisc
• Use Support Lib right from the beginning
• Use Activities to manage Fragments
• Use Fragments to implement the UI
• onCreate is monitored by the Android Runtime and is part of the UI Thread
 time consuming work needs to be done asynchronously (!)
• Style UI via style xml files not via specific view attributes in layout xml files
• Define a color palette (colors.xml), same for dimensions (dimens.xml)
• Prefix layout files (activity_, fragment_, listItem_, …)
• Re-use elements using <include> (and <merge> in the to be included layout file)
• compileTarget is your Frenemy, test thoroughly
• Don‘t set maxSdkVersion
• Be specific about your dependencies (2.2.0 not 2.2.+)
• Don‘t use too many libs (65k method limit!)
• Launcher icon(s) in mipmap folder when generating separate APKs for diff. densities

16. Let‘s check out some code 
DEMO

17. Topics we didn‘t talk about…
• Network / Communication
• Persistence
• Service / AsyncTask / Loader / Event Bus
• Permission System
• Sensors

18. Some links to get you started…
• Android Tutorials:
– http://developer.android.com/training/index.html
– https://www.udacity.com/courses/android
• Helpful Github Projects
– https://github.com/android10/Android-CleanArchitecture
– https://github.com/ribot/android-guidelines
– https://github.com/txusballesteros/Android-Clean-Testing
– https://github.com/ribot/android-boilerplate
• Exemplary Apps on Github to play around
– https://github.com/WhisperSystems/Signal-Android
– https://github.com/owncloud/android
• Icons:
– https://materialdesignicons.com/