Minds-on: Android. Session 1

Transcription

1 Minds-on: Android Session 1 Paulo Baltarejo Sousa Instituto Superior de Engenharia do Porto 2016

2 Outline Mobile devices Android OS Android architecture Android Studio Practice 1 / 33

3 2 / 33 Mobile devices

4 Overview Mobile devices have outsold traditional desktop and laptop computers continuously for nearly four years at this point. The definition of work on a computer is changing and adapting to what devices people are buying 1. Shopping goes mobile. Mobile shopping spiked 60 percent this year (2015) / 33

5 Mobile users Numbers 3 How often do you check your phone? Smartphone users check their phones an average of 150 times a day 4 The average person does it 110 times a day (and up to every 6 seconds in the evening)... some users unlocking their devices up to 900 times over the course of a day tech.firstpost.com/news-analysis/smartphone-users-check-their-phones-an-average-of-150-times-a-day html 5 seconds-evening.html 4 / 33

6 Mobile Operating Systems Mobile Operating System (OS) market share (Dec. 2015) / 33

7 6 / 33 Android OS

8 Overview Android is a mobile OS: Based on the Linux kernel Developed by Google. Designed primarily for mobile devices, such as smartphones and tablets, but nowadays there are specific versions for: Televisions, Cars, and Wear (for wrist watches) Variants of Android are also used on notebooks, game consoles, digital cameras, and other electronics / 33

9 Versions Android evolution 8 9 Android compatibility 10 8 cubettech.com/blog/android-1-0-to-android-m-the-story-of-mobile-evolution/ source.android.com/compatibility/index.html 8 / 33

10 How to develop Android apps Android applications are primarily written in the Java programming language. During development the developer creates the Android specific configuration files and writes the app logic in the Java programming language. The Android tooling converts these app files, transparently to the user, into an Android app (an apk file). When developers trigger the deployment in their Integrated Development Environment (IDE), the whole Android app is compiled, packaged, deployed and started. 9 / 33

11 10 / 33 Android architecture

12 Architecture 11 / 33

13 Runtime Each Android app runs in its own security sandbox: Each process has its own virtual machine (VM), so an app s code runs in isolation from other apps. Every app runs in its own Linux process. Android starts the process when a app is launched, then shuts down the process when it is no longer needed or when the system must recover memory for other applications. Since Android 5.0 Lollipop system, the Dalvik VM has been officially replaced by a new runtime called ART (Android RunTime). 12 / 33

14 Framework (I) activities: An activity is the key execution component. You need at least one activity in an app that deals with the User Interface (UI). An activity is implemented as a subclass of Activity. fragments: Fragments are relatively new to Android but very important in programming the UI. They are mini-activities. A fragment is implemented as a subclass of Fragment. intents: An Intent is a messaging object you can use to request an action from another app component. Although intents facilitate communication between components in several ways, there are three fundamental use-cases: To start an activity To start a service To deliver a broadcast 13 / 33

15 Framework (II) services: Typically services are long running programs that do not need to interact with the UI. A service is implemented as a subclass of Service. content providers: Apps could share data. Content providers manage access to a structured set of data. A content provider is implemented as a subclass of ContentProvider. broadcast receivers: A Broadcast receiver allows you to register for system or application events. All registered receivers for an event are notified by the Android runtime once this event happens. A broadcast receiver is implemented as a subclass of BroadcastReceiver and each broadcast is delivered as an Intent object. 14 / 33

16 App programming model Model-View-Controller (MVC) Actually, Android does not enforce MVC, this is considered a best practice for development. 15 / 33

17 16 / 33 Android Studio

18 Overview Android Studio 11 is the official IDE for Android apps development. It includes everything required for developing Android apps: Android SDK Tools Android Platform-tools Android platform versions Android system images (for the emulator) It is based on IntelliJ IDEA and offers 12 Flexible Gradle-based build system Build variants and multiple apk file generation Code templates to help you build common app features developer.android.com/sdk/index.html 12 developer.android.com/tools/studio/index.html 17 / 33

19 Setting up the development environment Get the Android Studio from Setting Up Java Install Android Studio SDK Manager Get SDK tools Get the support library for additional APIs Get Google Play services for even more APIs Install the packages Creating an AVD All this information can be found at: ~pbsousa/android/s1_1.pdf 18 / 33

20 IDE - General view 19 / 33

21 IDE - Code editor 20 / 33

22 IDE - Logcat 21 / 33

23 IDE - Toolbar and Project view Toolbar Project view modes 22 / 33

24 MVC Models: Shared Preferences SQLite Databases Network Connection Internal and External Storage Syncing to the Cloud Views XML files Controllers Java files 23 / 33

25 Class R All resource IDs are defined in your project s R class, which the aapt tool automatically generates. R class contains resource IDs for all the resources in your res/ directory. For each type of resource, there is an R subclass (for example, R.layout for all layout resources), and for each resource of that type, there is a static integer (for example, R.layout.activity main). This integer is the resource ID that you can use to retrieve your resource. 24 / 33

26 Android Manifest XML Every application must have a manifest.xml file in its root directory. The manifest file presents essential information about app to the Android system: Java package name for the application: the package name serves as a unique identifier for the application. The components of the application: the activities, services, broadcast receivers, and content providers. Permissions the application. 25 / 33

27 26 / 33 Practice

28 First App How to create an Android Studio project Running on emulator Running on a real Device All this information can be found at: ~pbsousa/android/s1_2.pdf 27 / 33

29 Building a Simple User Interface Android App (I) Linear Layout 28 / 33

30 Building a Simple User Interface Android App (II) Supporting Different Languages 29 / 33

31 Building a Simple User Interface Android App (III) Supporting Different Screens All this information can be found at: ~pbsousa/android/s1_3.pdf 30 / 33

32 List view based app (I) List View 31 / 33

33 List view based app (II) Option menu 32 / 33

34 List view based app (III) Context menu All this information can be found at: ~pbsousa/android/s1_4.pdf 33 / 33