Exam 1z0-819 topic 1 question 27 discussion

A. wrong public int compare(T o1, T o2) - must be implemeted B. wrong Because it missed generic type parameter should have Object type arguments public int compare (Object obj1, Object obj2) C. correct Anonymous with interface implementation Generic type parameter is String and method compare with String arguments D. wrong wrong return type

answer: AC A and C are the same Anonymous with interface as a result there is a valid comparable implementation D failed wrong return type B failed should have raw type arguments public int compare (Object obj1, Object obj2) {

Comparator use compare and String implement Comparable who use compareTo so C is correct

c , Comparator has method compare no compareTo, can used in method compare

Correct answer is C . //A is invalid because :The type new Comparator<String>(){} must implement the inherited abstract method Comparator<String>.compare(String, String) //B is invalid because : The type Comps must implement the inherited abstract method Comparator.compare(Object, Object) //D is invalid because : The return type is incompatible with Comparator.compare(Object, Object) and Illegal modifier for the local class Comps; only abstract or final is permitted

C is correct

Tested

c is correct