Let’s run with some standard Kotlin functions! Short and powerful, let, apply, with and run all have a receiver (this), may have an argument (it) and may have a return value. See the differences
Day 2 - KTX view padding
Extending existing APIs with default arguments usually makes everyone happy. Android KTX lets you set the padding on one side of a view using default parameters.
Powerful but hard to use - that’s how the text styling Spans API feels.
Android KTX adds extension functions for some of the most common spans and makes the API easier to use
[1/4] Specifically terrific? Domain specific languages can be made by using type safe builders. They make for clean APIs; and you can build them yourself too.
Write Kotlin (time * 2) faster with operator overloading. Objects like Path, Range or SpannableStrings naturally allow for operations like addition or subtraction. With Kotlin, you can implement your own operators
[1/2] Sequences are lists that never existed. A Sequence is a cousin of Iterator, lazily generating one value at a time. This matters when using map and filter - they’ll create Sequences instead of copying the list for every step!
[1/2] No more Util classes! Extend the functionality of a class by using extension functions. Put the name of the class you’re extending before the name of the method you’re adding.
Delegate your work to another class with by. Favor composition over inheritance with class delegation and reuse property accessor logic with delegator properties.
Kotlin lets you specify a function as inline - which means calls will be replaced with the function body. Breathe and make lambda-based APIs with zero overhead.
It’s good to be lazy! Defer the cost of expensive property initialization until they’re actually needed, by using lazy. The computed value is then saved and used for any future calls.
[1/3] Kotlin sealed classes let you easily handle error data. When combined with LiveData you can use one LiveData to represent both the success path and the error path. Way better than using two variables.
In Kotlin, everything is public by default! Well, almost. Kotlin has a rich set of visibility modifiers you can use as well: private, protected, internal. Each of them reduces the visibility in a different way.
Creating classes with one role: to hold data? Mark them as “data” classes. The default implementation of equals() is generated (so are hashCode(), toString(), and copy()) and checks for structural equality.
In Kotlin, classes can have mutable and read-only properties, with getters and setters generated by default. You can also implement custom ones if required.
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