Basic of Android Development

Transcript

1. Laurence de Villers @L_de_V Basic of Android Development

2. Basic of Android • Android Apps are written in Java

   and Kotlin • UI Screens are defined in XML • IDE Android Studio ( base on Intellij ) ◦ Android SDK ◦ Android Monitor • Terminal Commands (adb) • Apps run in a Virtual Marchine • Android Kernel is the Linex Kernel • Build tool is Gradle • App format = .apk

3. Code Definition and Examples Ressources • developer.android.com • Udacity (Android

   for Beginners and Android MicroDegree) • Android Arsenal ( Android developer portal with tools, libraries, and apps) • CodeLab: https://codelabs.developers.google.com/?cat=Android • Vocab : https://developers.google.com/android/for-all/vocab-words/

4. Kotlin

5. Basic of Kotlin What is Kotlin Is a language developed

   by JetBrains. 100% interoperable with Java A language that have Null Safety var b: String? = "abc" b = null // ok val l = b.length // error WHY? variable 'b' can be null var a: String = "abc" a = null // compilation error val l = a.length //ok

6. Basic of Kotlin Safe Call Operator, witten ?. // If

   'applETS' or 'applETS.mobileapp' is null the function is not called: applETS?.mobileapp?.android = creationOfAndroidMobileApp() val a = "Kotlin" val b: String? = null println(b?.length) println(a?.length) Safe Call can be chains Elvis Operator, witten ?: val l = b?.length ?: -1 In Java int l = b != null ? b.length : -1

7. Basic of Kotlin The !! Operator val l = b!!.length

   Safe Cast val aInt: Int? = a as? Int val VS var val is immutable same as the final modifier in java var is mutable (can be reassigned)

8. Android KTX Part of Jetpack Concise, readable code. A suite

   of libraries Android KTX, Testing KTX, ...

9. UI Screens are defined in XML

10. Common Android Views Helpful reference https://drive.google.com/file/d/0B5XIkMkayHgRMVljUVIyZzNmQUU/view https://developer.android.com/docs/

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16. View Groups ( Layout) • ConstraintLayout • CoordinatorLayout • RelativeLayout

    • LinearLayout • ListView • RecyclerView • ScrollView • CardView • etc.

17. Practice your view

18. Activity vs Fragment

19. What is the hardest part of Android Development?

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21. Retains value between onCreate and onDestroy // some transient state

    for the activity instance var gameState: String? = null override fun onCreate(savedInstanceState: Bundle?) { // call the super class onCreate to complete the creation of activity like // the view hierarchy super.onCreate(savedInstanceState) // recovering the instance state gameState = savedInstanceState?.getString(GAME_STATE_KEY) // set the user interface layout for this activity // the layout file is defined in the project res/layout/main_activity.xml file setContentView(R.layout.activity_main) }

22. Retains value between onCreate and onDestroy // We restore some

    state in onCreate(), while we can optionally restore // other state here, possibly usable after onStart() has completed. // The savedInstanceState Bundle is same as the one used in onCreate(). override fun onRestoreInstanceState(savedInstanceState: Bundle?) { textView.text = savedInstanceState?.getString(TEXT_VIEW_KEY) } // invoked when the activity may be temporarily destroyed (onStop), save the instance state here override fun onSaveInstanceState(outState: Bundle?) { outState?.run { putString(GAME_STATE_KEY, gameState) putString(TEXT_VIEW_KEY, textView.text.toString()) } // call superclass to save any view hierarchy super.onSaveInstanceState(outState) }
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24. Android Studio

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27. Gadle Custom build tool used to build android packages android

    { compileSdkVersion 28 defaultConfig { applicationId "com.ldevillers.applets_first_app" minSdkVersion 16 targetSdkVersion 28 versionCode 1 versionName "1.0" testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner" } buildTypes { release { minifyEnabled false proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro' } } } dependencies { implementation fileTree(dir: 'libs', include: ['*.jar']) implementation"org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version" implementation 'com.android.support:appcompat-v7:28.0.0' … }

28. Build Your First Android App in Koltin Codelab : bit.ly/applETS_Kotlin

29. Android Jetpack Accelerate App Development

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31. 95% supported devices

32. Want to learn more about Android ? Join the meetup

    GDG Montreal Android: android-montreal.com

33. THE END! Questions? Laurence de Villers @L_de_V