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

77.6 Adding the Repository

Add a new class named ProductRepository to the project, with the Class option selected.

The repository class will be responsible for interacting with the Room database on behalf of the ViewModel and will need to provide methods that use the DAO to insert, delete and query product records. With the exception of the getAllProducts() DAO method (which returns a LiveData object) these database operations will need to be performed on separate threads from the main thread using the AsyncTask class.

Remaining within the ProductRepository.kt file, add the code for the search AsyncTask. Also add a method named asyncFinished() which will be called by the query AsyncTask to return the search results to the repository thread:

package com.ebookfrenzy.roomdemo

 

import android.app.Application

import android.os.AsyncTask

import androidx.lifecycle.LiveData

import androidx.lifecycle.MutableLiveData

 

class ProductRepository(application...