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Android Development with Kotlin

You're reading from   Android Development with Kotlin Enhance your skills for Android development using Kotlin

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Product type Paperback
Published in Aug 2017
Publisher Packt
ISBN-13 9781787123687
Length 440 pages
Edition 1st Edition
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Authors (2):
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Marcin Moskala Marcin Moskala
Author Profile Icon Marcin Moskala
Marcin Moskala
Igor Wojda Igor Wojda
Author Profile Icon Igor Wojda
Igor Wojda
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Toc

Table of Contents (10) Chapters Close

Preface 1. Beginning Your Kotlin Adventure FREE CHAPTER 2. Laying a Foundation 3. Playing with Functions 4. Classes and Objects 5. Functions as First-Class Citizens 6. Generics Are Your Friends 7. Extension Functions and Properties 8. Delegates 9. Making Your Marvel Gallery Application

Object expression


An object expression is equivalent to Java's anonymous class. It is used to instantiate objects that might inherit from some class or that implements an interface. A classic use case is when we need to define objects that are implement an interface. This is how in Java we could implement the ServiceConnection interface and assign it to a variable in Java:

    ServiceConnection serviceConnection = new ServiceConnection() { 
        @Override 
        public void onServiceDisconnected(ComponentName name) { 
            ...
        } 
 
        @Override 
        public void onServiceConnected(ComponentName name, 
            IBinder service) 
        {
            ... 
        } 
    } 

The closest Kotlin equivalent of the preceding implementation is the following:

    val serviceConnection = object: ServiceConnection { 
 
     override fun onServiceDisconnected(name: ComponentName?) { } 
 
     override fun onServiceConnected(name: ComponentName?, 
         service: IBinder...
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