Exception-friendly functional interfaces named by the number of arguments: Fn0, Fn1, Fn2.... All of these have an applyEx() method that that throws an Exception and returns a result. Implementers should override the applyEx() method (this happens automatically when you use Java 8's lambda syntax). Each interface also has a default apply() method for consumers of this function to call. It re-throws all exceptions after wrapping any checked ones in unchecked RuntimeExceptions.

For simplicity, there are no primitive versions of these functions, no "void" return types, and no special-purpose funny names. If you don't want to return a result, declare the return type as ? and return null. Comparing just the Consumer interfaces from { @link java.util.function}: