irbull

MyInterface r2 = () -> 
  System.out.println("Hello, world");
  System.out.println("Goodbye, world!");

vs.

MyInterface r2 = () -> {
  System.out.println("Hello, world");
  System.out.println("Goodbye, world!");
};

irbull

In this simple example, we are taking a List<String> of names, sorting them, creating Person objects and printing the result. The first way uses single line lambda expressions:

names.stream().sorted((o1, o2) -> o1.compareTo(o2)).
  map(name -> new Person(name)).
  forEach(p -> System.out.println(p.getName()));

The second one wraps each expression in a bracket and makes the types explicit:

names.stream().sorted(( String o1, String o2 ) -> 
 {