1. Creating DTOs(POJOs/POCOs)
2. Default values for function parameters
3. Filtering a list
4. String Interpolation
5. Instance Checks
6. Traversing a map/list of pairs
7. Using ranges
8. Read-only list
9. Read-only map
10. Accessing a map
11. Lazy property
12. Extensions Functions
13. Create a Singleton
14. If not null shorthand
15. If not null and else shorthand
16. Executing a statement if null
17. Get first item of a possibly empty collection
18. Execute if not null
19. Map nullable value if not null
20. Return on when statement
21. try/catch expression
22. if expression
23. Builder-style usage of methods that return Unit
24. Single-expression functions
25. Calling multiple methods on an object instance('with')
class Turtle { fun penDown() fun penUp() fun turn(degrees: Double) fun forward(pixels: Double) } val myTurtle = Turtle() with(myTurtle) { //draw a 100 pix square penDown() for(i in 1..4) { forward(100.0) turn(90.0) } penUp() } |
26. Java 7's try with resources
val stream = Files.newInputStream(Paths.get("/some/file.txt")) stream.buffered().reader().use { reader -> println(reader.readText()) } |
27. Convenient form for a generic function that requires the generic type information
// public final class Gson { // ... // public <T> T fromJson(JsonElement json, Class<T> classOfT) throws JsonSyntaxException { // ... inline fun <reified T: Any> Gson.fromJson(json: JsonElement): T = this.fromJson(json, T::class.java) |
28. Consuming a nullable Boolean
val b: Boolean? = ... if (b == true) { ... } else { // `b` is false or null } |
