Programming Tutorial Bits: Kotlin Data Classes

Programming Tutorial Bits: Kotlin Data Classes




https://www.youtube.com/watch?v=Telif4fZtrs

This is a great place to start learning Kotlin if you have even basic Java experience.  More videos to come.


In this video we will learn:


  •  How to use data classes in Kotlin.
  •   How to decompile Kotlin code to understand what it provides
  •  What Kotlin improves on from Java with data classes
  •   We will also touch on Nullable and Non-Nullable types and what happens when we try to call a non Nullable type with null form Java (Oh noes!!!)

Clarifications: 


Auto Get and Set generation: 


  •  If the member is declared with var and is accessible to class users (not private etc) you have access to setters and getters - If it is declared with "val" this NO SETTERS are generated. "val" is essentially like declaring "final" in Java the world. 
  •  EXPERIMENT AND TRY IT OUT! :)

!! Not-Null assertion operator

I touched a little the not null assertion operator, double exclamation point "!!" and why you should generally avoid it.
  • I highly recommend reserving these to only test (not prod) code. This is typically a code smell that may indicate you need to refactor.
  • If your application ever encounters null with this operator you will get a null pointer exception
  • Failing fast is fine in cases where you never expect null, so there may be practical production cases for this.
  • In practice though, you'll prob find yourself sanitizing using question mark operator and Elvis "?:" (which I will touch on in a later video) and probably throwing more specific validation exceptions etc.

Resources:

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