Book Image

Mastering Android Development with Kotlin

By : Miloš Vasić
Book Image

Mastering Android Development with Kotlin

By: Miloš Vasić

Overview of this book

Kotlin is a programming language intended to be a better Java, and it's designed to be usable and readable across large teams with different levels of knowledge. As a language, it helps developers build amazing Android applications in an easy and effective way. This book begins by giving you a strong grasp of Kotlin's features in the context of Android development and its APIs. Moving on, you'll take steps towards building stunning applications for Android. The book will show you how to set up the environment, and the difficulty level will grow steadily with the applications covered in the upcoming chapters. Later on, the book will introduce you to the Android Studio IDE, which plays an integral role in Android development. We'll use Kotlin's basic programming concepts such as functions, lambdas, properties, object-oriented code, safety aspects, type parameterization, testing, and concurrency, which will guide you through writing Kotlin code in production. We'll also show you how to integrate Kotlin into any existing Android project.
Table of Contents (24 chapters)
Title Page
Credits
About the Author
Acknowledgments
About the Reviewer
www.PacktPub.com
Customer Feedback
Preface

Implementing drag and drop


Here, in the last section of this chapter, we will show you how to implement the drag and drop feature. It's a feature that you will probably need in most applications containing data in lists. Using lists is not mandatory for performing drag and drop, because you can drag anything (view) and release it anywhere where a proper listener is defined. For a better understanding of what we are talking about, we will show you an example of how to implement it.

Let's define a view. On that view, we will set a long press listener that will trigger the drag and drop operation:

    view.setOnLongClickListener { 
            val data = ClipData.newPlainText("", "") 
            val shadowBuilder = View.DragShadowBuilder(view) 
            view.startDrag(data, shadowBuilder, view, 0) 
            true 
   } 

We used the ClipData class to pass the data to drop a target. We defined dragListener like this and assigned it to a view where we expect it to drop:

    private val dragListener...