Exam 1z0-819 topic 1 question 41 discussion

Case (h) is of interest for such option as the incompatible parameter types in lambda expression with its functional interface. Types must match.

Tested: A and F.

A. foo( n -> Integer.toHexString(n) ) is a correct answer because it uses a lambda expression to define the implementation of the Function interface. The lambda expression takes an Integer as input and returns a String as output, which matches the expected input and output types of the Function interface. F. foo( Integer::toHexString ) is also a correct answer because it uses a method reference to define the implementation of the Function interface. The method reference refers to the toHexString method of the Integer class, which takes an Integer as input and returns a String as output, matching the expected input and output types of the Function interface.

Answer: AF

A & F are correct because in (int n ) -> Integer.hexString(n) -- there is no need of parameterType because it is already declared in further function.

Correct answer is A & F