Oracle Exam 1Z0-819 Topic 8 Question 88 Discussion

Actual exam question for Oracle's 1Z0-819 exam

Question #: 88
Topic #: 8

[All 1Z0-819 Questions]

Given:

and

Which two method definitions at line n1 in the Bar class compile? (Choose two.)

Apublic List<Number> foo(Set<String> m) {...}

Bpublic List<Integer> foo(Set<CharSequence> m) {...}

Cpublic List<Integer> foo(TreeSet<String> m) {...}

Dpublic List<Object> foo(Set<CharSequence> m) {...}

Epublic ArrayList<Integer> foo(Set<String> m) {...}

Fpublic ArrayList<Number> foo(Set<CharSequence> m) {...}

Show Suggested Answer

Suggested Answer: C, F

by Malinda at Aug 26, 2024, 06:07 AM

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Emelda

7 months ago

I think option C will compile because it uses the correct parameter type and return type.

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Lonna

8 months ago

But options B and F use incorrect parameter types, so they won't compile.

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Nieves

8 months ago

Hold up, why isn't C correct? TreeSet is a subtype of Set, so that should work, right?

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Lonny

8 months ago

This question is making my brain hurt. I should have studied more for this exam.

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Terrilyn

7 months ago

Bob

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Ty

7 months ago

Alice

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Lucy

8 months ago

I'm pretty sure the answer is B and D. The return type can be a subclass of the declared type, and the parameter type can be a supertype or subtype.

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Alonso

8 months ago

I disagree, I believe options B and F will compile because they have the correct return types.

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Tuyet

8 months ago

Haha, whoever came up with these options is trying to trick us. I'm just going to guess and hope for the best.

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Delpha

7 months ago

I agree, those seem like the most likely choices.

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Delpha

7 months ago

I think options B and F will compile.

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Lonna

8 months ago

I think options A and E will compile because they both use the correct parameter types.

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Georgene

8 months ago

Wait, isn't D also correct? Object is a supertype of Integer, so that should compile too.

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Marilynn

8 months ago

The correct answer has to be B and E. The method signature has to use a covariant return type and the parameter type has to be a supertype or subtype of the declared type.

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Lore

7 months ago

And the parameter type has to be a supertype or subtype of the declared type.

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Teddy

8 months ago

Yes, you're right. The method signature needs a covariant return type.

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Micheal

8 months ago

I think the correct answers are B and E.

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