Book Image

Android Studio 4.0 Development Essentials - Kotlin Edition

By : Neil Smyth
Book Image

Android Studio 4.0 Development Essentials - Kotlin Edition

By: Neil Smyth

Overview of this book

Kotlin as an Android-compatible programming language is becoming increasingly popular. Fully updated for Android Studio 4.0, this book will teach you the skills necessary to develop Android-based applications using Kotlin. Starting with the basics, this book outlines the steps necessary to set up Android development and testing environments, and goes on to introduce you to programming in Kotlin. You’ll practice Java to Kotlin code conversion and explore data types, operators, expressions, loops, functions, as well as the basics of OOP in Kotlin. You’ll then learn about Android architecture components and advanced topics, such as intents, touchscreen handling, gesture recognition, multi-window support integration, and biometric authentication. As you make progress, you’ll explore Android Studio 4.0’s key features, including layout editor, direct reply notifications, and dynamic delivery. You’ll also delve into Android Jetpack and create a sample app project using ViewModel, the Android Jetpack component. Finally, you will upload your app to Google Play Console and model the build process using Gradle. By the end of this Android book, you’ll be fully prepared to develop applications using Android Studio 4.0 and Kotlin.
Table of Contents (97 chapters)
97
Index

66.3 Designing the User Interface

The user interface will consist of a button to launch coroutines together with a Seekbar to specify how many coroutines are to be launched asynchronously each time the button is clicked. As the coroutines execute, a TextView will update when individual coroutines start and end.

Begin by loading the activity_main.xml layout file and add the Button, TextView and SeekBar objects so that the layout resembles that shown in Figure 66-1:

Figure 66-1

To implement the layout constraints shown above begin by clearing all constraints on the layout using the toolbar button. Shift-click on the four objects so that all are selected, right-click over the top-most TextView and select the Center -> Horizontally menu option. Right-click once again, this time selecting the Chains -> Create Vertical Chain option.

Select the SeekBar and change the layout_width property to 0dp (match_constraints) before adding a 24dp margin on the left and right hand...