Book Image

Android Studio 4.2 Development Essentials - Java Edition

By : Neil Smyth
Book Image

Android Studio 4.2 Development Essentials - Java Edition

By: Neil Smyth

Overview of this book

Android Studio is an Integrated Development Environment based on the JetBrains IntelliJ IDEA. It provides developers with a unique platform to design and develop Android apps using various developer tools. The new Android Studio 4.2 has an upgraded IntelliJ platform and a variety of new features designed to improve the productivity of Android app developers. Fully updated for Android Studio 4.2, the objective of this book is to help you master the skills necessary to develop Android applications using Java as the programming language. This book begins by outlining the steps necessary to set up an Android development and testing environment and introducing programming in Java, describing data types, flow control, functions, lambdas, and object-oriented programming. It includes an overview of Android Studio, covering areas such as tool windows, the code editor, and the Layout Editor tool. An introduction to Android architecture is followed by an in-depth explanation of the design of Android applications and user interfaces using the Android Studio environment. Early chapters detail Android Architecture components like view models, lifecycle management, Room database access, the Database Inspector, app navigation, live data, and data binding. Advanced topics such as intents are also covered, as are touch screen handling, gesture recognition, and the recording and playback of audio. You will also explore printing, transitions, cloud-based file storage, and foldable device support. Detailed descriptions of the concepts of material design are provided, including the use of floating action buttons, Snackbars, tabbed interfaces, card views, navigation drawers, and collapsing toolbars. Some key features of Android Studio 4.2 and Android discussed in-depth include the Layout Editor, the ConstraintLayout and ConstraintSet classes, MotionLayout Editor, view binding, constraint chains, barriers, and direct reply notifications. Later chapters cover advanced features of Android Studio such as App Links, Dynamic Delivery, the Android Studio Profiler, Gradle build configuration, and submitting apps to the Google Play Developer Console.
Table of Contents (87 chapters)
87
Index

56.7 Implementing a Thread Handler

Thread handlers are implemented in the main thread of an application and are primarily used to make updates to the user interface in response to messages sent by other threads running within the application’s process.

Handlers are subclassed from the Android Handler class and can be used either by specifying a Runnable to be executed when required by the thread, or by overriding the handleMessage() callback method within the Handler subclass which will be called when messages are sent to the handler by a thread.

For the purposes of this example, a handler will be implemented to update the user interface from within the previously created thread. Load the MainActivity.java file into the Android Studio editor and modify the code to add a Handler instance to the activity:

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import android.os.Handler;

import android.os.Message;

import android.os.Looper;

public class MainActivity extends AppCompatActivity {

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