Book Image

Android Studio 3.5 Development Essentials - Java Edition

By : Neil Smyth
Book Image

Android Studio 3.5 Development Essentials - Java Edition

By: Neil Smyth

Overview of this book

Android applications have become an important part of our daily lives and lots of effort goes into developing an Android application. This book will help you to build you own Android applications using Java. Android Studio 3.5 Development Essentials – Java Edition first teaches you to install Android development and test environment on different operating systems. Next, you will create an Android app and a virtual device in Android Studio, and install an Android application on emulator. You will test apps on physical Android devices, then study Android Studio code editor and constraint layout, Android architecture, the anatomy of an Android app, and Android activity state changes. The book then covers advanced topics such as views and widgets implementation, multi-window support integration, and biometric authentication, and finally, you will learn to upload your app to Google Play console and handle the build process with Gradle. By the end of this book, you will have gained enough knowledge to develop powerful Android applications using Java.
Table of Contents (86 chapters)
86
Index

33.3 Implementing the Observer

Now that the conversion result is contained within a LiveData instance, the next step is to configure an observer within the UI controller which, in this example, is the MainFragment class. Locate the MainFragment.java class (app -> java -> <package name> -> MainFragment), double-click on it to load it into the editor and modify the onActivityCreated() method to create a new Observer instance named resultObserver:

package com.ebookfrenzy.viewmodeldemo.ui.main;

 

import androidx.lifecycle.Observer;

.

.

@Override

public void onActivityCreated(@Nullable Bundle savedInstanceState) {

.

.

    dollarText = getView().findViewById(R.id.dollarText);

    resultText = getView().findViewById(R.id.resultText);

    convertButton = getView().findViewById(R.id.convertButton);

 

    resultText.setText(mViewModel.getResult()...