Book Image

Android Programming for Beginners - Third Edition

By : John Horton
Book Image

Android Programming for Beginners - Third Edition

By: John Horton

Overview of this book

Do you want to make a career in programming but don’t know where to start? Do you have a great idea for an app but don't know how to make it a reality? Or are you worried that you’ll have to learn Java programming to become an Android developer? Look no further! This new and expanded third edition of Android Programming for Beginners will be your guide to creating Android applications from scratch. The book starts by introducing you to all the fundamental concepts of programming in an Android context, from the basics of Java to working with the Android API. You’ll learn with the help of examples that use up-to-date API classes and are created within Android Studio, the official Android development environment that helps supercharge your mobile application development process. After a crash course on the key programming concepts, you’ll explore Android programming and get to grips with creating applications with a professional-standard UI using fragments and storing user data with SQLite. This Android Java book also shows you how you can make your apps multilingual, draw on the screen with a finger, and work with graphics, sound, and animations. By the end of this Android programming book, you'll be ready to start building your own custom applications in Android and Java.
Table of Contents (30 chapters)

Device detection mini-app

The best way to learn about detecting and responding to devices and their varying attributes (screens, orientations, and so on) is to make a simple app:

  1. Create a new Empty Activity project and call it Device Detection. Leave all the other settings as their defaults.
  2. Open the activity_main.xml file in the design tab and delete the default Hello world! TextView.
  3. Drag a Button onto the top of the screen and set its onClick property to detectDevice. We will code this method in a minute.
  4. Drag two TextView widgets onto the layout, one below the other, and set their id properties to txtOrientation and txtResolution.
  5. Check you have a layout that looks something like this next screenshot:

    Note

    I have stretched my widgets (mainly horizontally) and increased the textSize attributes to 24sp to make them clearer on the screen, but this is not required for the app to work correctly.

    Figure 24.3– Layout check

  6. Click the Infer Constraints...