Kotlin Programming: The Big Nerd Ranch Guide, First Edition

Function Types in Java

Function types and anonymous functions are novel inclusions in the Kotlin programming language that provide a streamlined syntax for communicating between components. Their concise syntax is made possible via the -> operator, but lambdas are not supported in versions of Java prior to Java 8.

So what do these function types look like when called from Java? The answer may seem deceptively simple: In Java, your function type is represented by an interface with a name like FunctionN, where N is the number of arguments taken as parameters.

To see this in practice, add a function type called translator to Hero.kt. translator should take a String, lowercase it, capitalize the first letter, and print out the result. ...