Java SE 11 Developer (1Z0-819) — Question 38

Given the code fragment:
public void foo(Function<Integer, String> fun) {...}
Which two compile? (Choose two.)

Answer options

• A. foo( n -> Integer.toHexString(n) )
• B. foo( toHexString )
• C. foo( n -> n + 1 )
• D. foo( int n -> Integer.toHexString(n) )
• E. foo( n -> Integer::toHexString )
• F. foo( Integer::toHexString )
• G. foo( n::toHexString )
• H. foo( (int n) -> Integer.toHexString(n) )

Correct answer: A, F

Explanation

Option A is valid as it uses a lambda expression that matches the expected Function<Integer, String> type. Option F is also correct as it uses a method reference that refers to the method Integer::toHexString, which matches the required function signature. The other options either use incorrect syntax or do not conform to the expected function type.