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

32.6 Associating the Fragment with the View Model

Clearly, there needs to be some way for the fragment to obtain a reference to the ViewModel in order to be able to access the model and observe data changes. A Fragment or Activity maintains references to the ViewModels on which it relies for data using an instance of the ViewModelProvider class.

A ViewModelProvider instance is created via a call to the ViewModelProviders.of() method from within the Fragment. When called, the method is passed a reference to the current Fragment or Activity and returns a ViewModelProvider instance as follows:

ViewModelProvider viewModelProvider = ViewModelProviders.of(fragment);

Once the ViewModelProvider instance has been created, the get() method can be called on that instance passing through the class of specific ViewModel that is required. The provider will then either create a new instance of that ViewModel class, or return an existing instance:

ViewModel viewModel = viewModelProvider...