Given the method below, what is the widest valid return type for methodA on line 3? public class ReturnIt { returnType methodA(byte x, double y) // Line 3 { return (long)x / y * 2; } }
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Aint
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Bbyte
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Clong
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Ddouble
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ENumber
Answer
Correct Answer: double
Explanation
Introduction / Context:Expression type promotion in Java determines the resulting type of arithmetic expressions. Choosing a compatible return type requires analyzing how primitives are promoted.
Given Data / Assumptions:
xis a byte, explicitly cast to long.yis a double.- The expression is
(long)x / y * 2.
Concept / Approach:Division involving a double promotes the other operand to double, and the result is double. Multiplying a double by an int literal 2 yields a double. Therefore, the expression overall is of type double, and the return type must be compatible (double or wider in the sense of assignment compatibility; here the precise primitive type is double).
Step-by-Step Solution:
Cast:(long)x → long.Operation: long / double → double.Operation: double * 2 → double.Conclusion: method must return double.Verification / Alternative check:Changing return type to double compiles; using long or int requires an explicit cast (and loses precision).
Why Other Options Are Wrong:int, byte, and long are narrower than double for this expression; Number is not a primitive and does not match the expression type without boxing and is not a valid primitive return type here.
Common Pitfalls:Assuming the initial cast to long dictates the overall type; forgetting that any double operand dominates.
Final Answer:double