Book Image

Android Studio 4.0 Development Essentials - Java Edition

By : Neil Smyth
Book Image

Android Studio 4.0 Development Essentials - Java Edition

By: Neil Smyth

Overview of this book

Android rolls out frequent updates to meet the demands of the dynamic mobile market and to enable its developer community to lead advancements in application development. This book focuses on the updated features of Android Studio (the fully integrated development environment launched by Google) to build reliable Android applications using Java. The book starts by outlining the steps necessary to set up an Android development and testing environment. You’ll then learn how to create user interfaces with the help of Android Studio Layout Editor, XML files, and by writing the code in Java. The book introduces you to Android architecture components and advanced topics such as intents, touchscreen handling, gesture recognition, multi-window support integration, and biometric authentication, and lets you explore key features of Android Studio 4.0, including the layout editor, direct reply notifications, and dynamic delivery. You’ll also cover Android Jetpack in detail and create a sample app project using the ViewModel component. Finally, you’ll upload your app to the Google Play Console and handle the build process with Gradle. By the end of this book, you’ll have gained the skills necessary to develop applications using Android Studio 4.0 and Java.
Table of Contents (88 chapters)
88
Index

28.1 Implementing Common Gesture Detection

When a user interacts with the display of an Android device, the onTouchEvent() method of the currently active application is called by the system and passed MotionEvent objects containing data about the user’s contact with the screen. This data can be interpreted to identify if the motion on the screen matches a common gesture such as a tap or a swipe. This can be achieved with very little programming effort by making use of the Android GestureDetectorCompat class. This class is designed specifically to receive motion event information from the application and to trigger method calls based on the type of common gesture, if any, detected.

The basic steps in detecting common gestures are as follows:

1. Declaration of a class which implements the GestureDetector.OnGestureListener interface including the required onFling(), onDown(), onScroll(), onShowPress(), onSingleTapUp() and onLongPress() callback methods. Note that this can...