method-reference

When I want to refer to the method in the current scope I still need to specify class name (for static methods) or this before :: operator. For example, I need to write: import java.util.stream.Stream; public class StreamTest { public static int trimmedLength(String s) { return s.trim().length(); } public static void main(String[] args) { System.out.println(Stream.of(" aaa ", " bb ", " c ") .mapToInt(StreamTest::trimmedLength).sum()); } } It's not so big problem for this , but sometimes look overcrowded for static methods as the class name can be quite long. It would be nice if compiler

I have an async method with a completeablefuture result: public CompletableFuture<DogLater> asyncDogLater(String dogName){} I have a list of dogs: List<Dog> dogs; Now, I want to create a map from the dog's name to the Completeablefuture: Map<String, CompletableFuture<DogLater>> map; After checking this and this I was trying to do so: Map<String, CompletableFuture<DogLater>> completableFutures = dogs.stream() .collect( Collectors.toMap(Dog::getName, asyncDogLater(Dog::getName ))); But the compiler complains that the first Dog::getName is problematic since: Non-static method cannot be referenced

I have an example Java code using method reference that I want to rewrite to Kotlin. Java version is using method reference, solution is short and clear. But on the other hand I cannot use method reference in Kotlin. The only version that I've managed to write is one presented below. It seems like Function3 { s: String, b: Boolean, i: Int -> combine(s, b, i) } could be written in cleaner way (if possible method reference would be perfect). I'm new to Kotlin so I'll be grateful for any clues. Java import io.reactivex.Observable; public class TestJava { Observable<String> strings() { return

I have a need to work through a list and for each item call a different method on a target object. It seems elegant that I could just create a list of method references to do this, so for each index in the list, I could call the appropriate method reference that corresponds to it. private final static List<Consumer<String>> METHODS = (List<Consumer<String>>) Arrays.asList( TargetClass::setValue1, TargetClass::setValue2, TargetClass::setValue3, TargetClass::setValue4, TargetClass::setValue5); However, Eclipse is flagging these with the error The target type of this expression must be a

in a lecture I gave at my company I suggested converting any complex lambda to a method reference (more readable and better debug and testing) and was asked if it is always possible. I searched and could not find a lambda that cannot be replaced with method reference. am I right? (lambda can always be replaced with method reference) Method reference cannot capture variables. So a capturing lambda cannot be directly converted to a method reference. For example, int x = 1; numbers.replaceAll(n -> n + x); In some cases, if only one variable is captured, it might be possible to convert lambda to a