To start you should understand 2 fundamental Android concepts: Android app can have multiple entry points (Main activiyty, notifications, broadcast recivers) and your apps should adapt to different device configurations (screen size, specif hardware). Do not worry! Android provide you the API's and tools to apply those two concepts easily.

This tutorial walks through the following concepts:

• First look of the code of an Activity.
• First look to the main components in an Android project (project structure, folders and files).
• Basic layout design. Definition of a constraint layout, constraints, attribute definition
• Intro to the communication between activities

Resource:

• Official: Android developer guidelines
• Code of the app in this repo: 1-first-app

• Android Programming: The Big Nerd Ranch Guide

• Android Development with Kotlin

• Kotlin programming: The Big Nerd Ranch Guide

• Kotlin for Android developers

• Project and Code Guidelines by ribot

• A successful XML naming convention

• [Android - Building a layout from Scratch using ConstraintLayout - and Q&A #RiggarooLive] https://www.youtube.com/watch?v=h1LHzObflwo

• https://antonioleiva.com/mvp-android/
• https://dzone.com/articles/model-view-presenter-for-andriod Notes: in this example the presenter is also oriented to interface. I think is overthinking because the operations are gonna be delegate to the interactor, so the presenter will host minimum implementation, therefore oriented to interface maybe is too overthinking.
• https://hackernoon.com/basics-of-mvp-the-android-way-f75da407019d
• https://medium.com/cr8resume/make-you-hand-dirty-with-mvp-model-view-presenter-eab5b5c16e42
• http://macoscope.com/blog/model-view-presenter-architecture-in-android-applications/
• MVP Guidelines https://medium.com/@cervonefrancesco/model-view-presenter-android-guidelines-94970b430ddf

• Reading - Android Programming: The Big Nerd Ranch Guide

  54% - Current: Chapter 19

• Reading - Kotlin programming: The Big Nerd Ranch Guide

  7% - Current: Chapter 2

• Learning MVP Pattern

• An #androidDev collection of Live Templates for Android Studio

• Splash Screens the Right Way

Resources pending the review.

• https://kotlinlang.org/docs/reference/coding-conventions.html
• https://developer.android.com/kotlin/style-guide
• [ ] Code labs Google. https://codelabs.developers.google.com/?cat=Android
• [ ] Video. Conference talk about activity Lifecycle
• [ ] Patterns: MVP
• [ ] Patterns: MVVM
• [ ] Article about clean Architecture: https://erikcaffrey.github.io/ANDROID-clean-architecture/
• [ ] Android Architecture Components Guide - https://developer.android.com/topic/libraries/architecture/ - https://riggaroo.co.za/android-architecture-components-looking-room-livedata-part-1/ - https://riggaroo.co.za/android-architecture-components-looking-viewmodels-part-2/ - https://riggaroo.co.za/android-architecture-components-looking-lifecycles-part-3/ - https://www.youtube.com/watch?reload=9&v=9QrFMsihBAo - https://github.com/googlesamples/android-architecture-components - https://codelabs.developers.google.com/codelabs/android-persistence/index.html#0 - https://codelabs.developers.google.com/codelabs/constraint-layout/index.html#0
• [ ] Work with network - https://www.tutorialspoint.com/restful/ - http://square.github.io/retrofit/ - http://square.github.io/okhttp/ - https://developer.android.com/studio/profile/network-profiler - https://www.charlesproxy.com/
• [ ] Continuous Integration for Android - Jenkins - BuddyBuild - Cricle CI - Travis
• [ ] Code quality - Code Quality Tools - Sonar - FindBugs - Checkstyle - Android Lint
• [ ] Matering Layouts - FrameLayout - RelativeLayout - LinearLayout - ConstraintLayout - CoordinatorLayout - Supporting different screen sizes - https://developer.android.com/training/multiscreen/screensizes - ConstraintLayout - https://codelabs.developers.google.com/codelabs/constraint-layout/index.html#0
• [ ] Build systems - Build System - Gradle - https://gradle.org/ - Configure the build - https://developer.android.com/studio/build/
• [ ] Testing - Android Testing Support Library - https://developer.android.com/training/testing/ - Espresso - https://developer.android.com/training/testing/espresso/basics - JUnit - https://junit.org/junit4/ - Codelabe testing - https://codelabs.developers.google.com/codelabs/android-testing/index.html#0 https://codelabs.developers.google.com/codelabs/android-perf-testing/index.html#0
• [ ] Releasing - Releasing your Android apps - Preparing your app for release - https://developer.android.com/studio/publish/preparing - App Signing - https://developer.android.com/studio/publish/app-signing - Versioning your App - https://developer.android.com/studio/publish/versioning - ProGuard - https://developer.android.com/studio/build/shrink-code
• [ ] Security - Security Tips on Android - https://developer.android.com/training/articles/security-tips.html - Certificate Pinning - https://square.github.io/okhttp/3.x/okhttp/okhttp3/CertificatePinner.html - SafetyNet API - https://developer.android.com/training/safetynet/ - Android Keystore System - https://developer.android.com/training/articles/keystore
• [ ] https://android.jlelse.eu/10-things-new-android-developers-can-relate-to-afd82791faab
• [ ] https://google.github.io/styleguide/javaguide.html
• [ ] Service, IntentService and their lifecycle: - https://developer.android.com/guide/components/services - https://medium.com/@kevalpatel2106/how-to-handle-background-services-in-android-o-f96783e65268
• [ ] Broadcast Receivers - https://android.jlelse.eu/local-broadcast-less-overhead-and-secure-in-android-cfa343bb05be
• [ ] Content Providers - https://developer.android.com/guide/topics/providers/content-providers - https://medium.com/@paulnunezm/steps-for-creating-a-content-provider-ab376d661613 - https://medium.com/@sanjeevy133/an-idiots-guide-to-android-content-providers-part-1-970cba5d7b42 - https://medium.com/@sanjeevy133/an-idiots-guide-to-android-content-providers-part-2-7ccfbc88d75c
• [ ] Tasks and the Back Stack https://medium.com/androiddevelopers/tasks-and-the-back-stack-dbb7c3b0f6d4 https://android.jlelse.eu/android-activity-launch-mode-e0df1aa72242 https://medium.com/@iammert/android-launchmode-visualized-8843fc833dbe https://blog.mindorks.com/android-task-and-back-stack-review-5017f2c18196
• [ ] Debugging your app https://developer.android.com/studio/debug/ https://developer.android.com/studio/debug/
• [ ] Context in Android
• [ ]Android Views and Layouts https://medium.com/androiddevelopers/layouts-attributes-and-you-9e5a4b4fe32c https://medium.com/@geekanamika/android-beginners-views-layouts-657a5bbeebe2
• [ ] Android Themes and Styles https://youtu.be/TIHXGwRTMWI https://youtu.be/Jr8hJdVGHAk
• [ ] Fragments https://developer.android.com/guide/components/fragments https://medium.com/@bherbst/managing-the-fragment-back-stack-373e87e4ff62 https://android.jlelse.eu/the-dark-side-of-fragments-ca0f871b1199
• [ ] ViewPager https://developer.android.com/reference/android/support/v4/view/ViewPager https://android.jlelse.eu/creating-an-intro-screen-for-your-app-using-viewpager-pagetransformer-9950517ea04f
• [ ] RecyclerView https://youtu.be/KhLVD6iiZQs https://youtu.be/LqBlYJTfLP4 https://youtu.be/TS_J0Qw4zl0
• [ ] Shared Preferences https://android.i-visionblog.com/working-with-android-shared-preferences-4668efa298a8
• [ ] Sqlite https://medium.com/@valokafor/ultimate-guide-to-android-sqlite-database-44cc8636a4ec
• [ ] Threading https://medium.com/@ankit.sinhal/understanding-of-asynctask-in-android-8fe61a96a238
• [ ] Book: Efficient Android Threading: Asynchronous Processing Techniques for Android Applications https://www.amazon.com/Efficient-Android-Threading-Asynchronous-Applications/dp/1449364136/ref=as_li_ss_tl?s=books&ie=UTF8&qid=1515094900&sr=1-1&keywords=efficient+android+threading&linkCode=sl1&tag=xgentechnical-20&linkId=85f8342ab0f8016cfc279bd3eeee0940
• [ ] ThreadPoolExecutor
• [ ] Looper, Handler, HandlerThread
• [ ] HTTP and REST https://code.tutsplus.com/tutorials/a-beginners-guide-to-http-and-rest--net-16340
• [ ] Networking in Android apps https://www.raywenderlich.com/2-android-networking-tutorial-getting-started
• [ ] Notifications https://developer.android.com/guide/topics/ui/notifiers/notifications https://youtu.be/WzRSpZpw2wg
• [ ] Location and Maps https://developer.android.com/guide/topics/location/
• [ ] Android Sensors https://developer.android.com/guide/topics/sensors/sensors_overview
• [ ] Localization and Internationalization https://youtu.be/Z51wN9wCao0 https://developer.android.com/training/basics/supporting-devices/languages https://developer.android.com/training/basics/supporting-devices/languages
• [ ] Run Time Permissions https://developer.android.com/training/permissions/requesting https://youtu.be/f17qe9vZ8RM https://youtu.be/5xVh-7ywKpE
• [ ] App Standby and Doze Mode https://youtu.be/p6ZiDZBgPY8
• [ ] Android Support Libraries https://youtu.be/
  https://developer.android.com/topic/libraries/support-library/
• [ ] Material Design https://youtu.be/vx3TXN6ipAg https://youtu.be/EjTJIDKT72M https://youtu.be/9LUHFkPVYNo
• [ ] Android Build System https://youtu.be/OOEDKf06WqA https://youtu.be/Xw6CKEsWvxo