Java 11 and 12 – New Features

Explicitly-typed lambda expressions

A lambda expression that explicitly specifies the type of all of its input parameters is referred to as an explicitly-typed lambda expression. The following code illustrates a few examples (with the input parameters in bold):

(Integer age) -> age > 10;                      // input Integer,                                                 // return Boolean 
(Integer age) -> age > 10? "Kid" : "Not a Kid"; // input Integer,                                                 // return String 
(Integer age) -> {System.out.println();};       // input Integer,                                                 // return void 
() -> {return Math.random() + "Number";};       // input none,                                                // return String 
(String name, List<Person> list) -> { 
                               return ( 
                                   list.stream() 
                                       .filter(e ->                                                     e.getName().startsWith(name)) 
                                       .map(Person::getAge) 
                                       .findFirst() 
                                   ); 
                               };               // input name,                                                 // List<person>  // return ...