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

84.5 Designing the User Interface

Once the new project has been created, select the activity_main.xml file from the Project tool window and with the Layout Editor tool in Design mode, select the “Hello World!” TextView and delete it from the layout.

Drag and drop three Button views onto the layout. The positioning of the buttons is not of paramount importance to this example, though Figure 84-1 shows a suggested layout using a vertical chain.

Configure the buttons to display string resources that read Play, Record and Stop and give them view IDs of playButton, recordButton, and stopButton respectively.

Select the Play button and, within the Attributes panel, configure the onClick property to call a method named playAudio when selected by the user. Repeat these steps to configure the remaining buttons to call methods named recordAudio and stopAudio respectively.

Figure 84-1