January 2017
Intermediate to advanced
420 pages
9h 25m
English
Content preview from Programming KotlinBecome an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
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Overriding rules
You decided your new class has to redefine one of the methods inherited from one of the parent classes. This is known as overriding; I have already used it in the previous chapter. If you have already programmed in Java, you will find Kotlin a more explicit language. In Java, every method is virtual by default; therefore, each method can be overridden by any derived class. In Kotlin, you would have to tag the function as being opened to redefine it. To do so, you need to add the open keyword as a prefix to the method definition, and when you redefine the method, you specifically have to mark it using the override keyword:
abstract class SingleEngineAirplane protected constructor() { abstract fun fly() } class CesnaAirplane : SingleEngineAirplane() ...Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
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I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
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I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.