Answers for "what needs to be implemented to use lambda expression in java"

lambda expression java

public class TestLambda {

   public static void main(String args[]) {
      List<String> lowerCaseStringsList = Arrays.asList("a","b","c");
     // the :: notation is the lambda expression
     // it's the same as the anonymous function s -> s.toUpperCase()
      List<String> upperCaseStringsList = lowerCaseStringsList.stream().
        map(String::toUpperCase).
        collect(Collectors.toList());
   }   
}