Exam 1z0-819 topic 1 question 3 discussion

B ✅ -> overrides: Same method signature including return type C ✅ -> overloads: Same method signature including return type, overloads with a subclass as method parameter

subtype of List<Integer> is ArrayList<Integer> so we can consider BCE B is the same - overriding C - different parameter list - overloading E - should be same generics answer: BC

answer: BC A. not correct there is a same erasure for method signature but different generics for the parameter variable. So there is no overriding. B. correct same signature method and the return part C. correct overloading same method name but different parameter D. not correct same signature including parameter variable generic but incompatible return type (according to Liskov substitution principle) E. is not correct there is a same erasure for method signature but different generics for the parmeter variable. So there is no overriding. F. not correct same signature including parameter generic but incompatible return type (accotding to Liskov substitution principle) It will work for ArrayList<Integer> return type.

File Foo.java import java.util.List; import java.util.Set; public class Foo { public List<Integer> foo(Set<CharSequence> m) { return null; } } File Bar.java import java.util.List; import java.util.Set; import java.util.TreeSet; public class Bar extends Foo { // line n1. B //public List<Integer> foo(Set<CharSequence> m) { // return null; //} // line n1. C public List<Integer> foo(TreeSet<String> m) { return null; } } Choose B, C.

Tested: B and C.

the answer is B and C, B is overriding and C is overloading

This is a question about method overriding in Java. The method foo in the Bar class must have the same signature as the foo method in the Foo class to override it. This means that the return type and the parameter types must be the same. Therefore, the correct answers are B and D. Both of these options have a return type of List<Integer> and a parameter type of Set<CharSequence>, which matches the signature of the foo method in the Foo class.

F is not for returning Incompatible type and E is not for Name-Clash error in Set parameter. So correct answers is BC

BC is correct not CF since F returning incompatible type.

BC is correct

BC is correct

BC, not F, because returns "attempting to use incompatible return type"