eobermuhlner / hello-kotlin Goto Github PK

This is a playground for Kotlin development.

Best Kotlin features:

• properties instead of fields
  • no more getter/setter functions
  • property delegation
• null safe types
  • compiler enforces null safety
  • always know when you need to check
  • smart casting after checking for null
  • better operators: ?. !!. ?:
• type inference
  • less boiler plate code
  • (please use in moderation)
• better function calls
  • default values
  • named arguments
  • last argument can be written outside () if lambda function
• destructuring
  • assign components of an instance into several variables - val (name, age) = person
• extension functions
  • enhance class functionality even if you have no control over the code
• operator overloading
  • useful for equality and comparisons (== != and < <= > >=)
  • useful for math classes (+ - * / % ! .. ++ -- += ...)
  • useful for containers and DSL ((), [])
  • (please use in moderation)
• compact class declarations
  • constructor with properties as part of class declaration
  • classes are final per default (use open or sealed)
• enforced primary constructors
  • secondary constructor must end up calling the single primary constructor
• good handling of immutable vs. mutable states
  • language design is biased in favor of immutability
  • mutable and immutable collection classes
• improved generics
  • in and out instead of producer-extends and consumer-super
  • use reified to prevent type erasure in inline functions
• language allows designing nice DSLs
  • generally less clutter (see all of the above)
  • lambda function with receiver
  • single lambda argument can be omitted
  • infix functions
• ... many others ...