This 1Z0-811 practice question tests your understanding of arrays and methods. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A method is designed to compute the average of an array of test scores. What should the method return if the array is empty (length 0)?
Return 0.0
Default value for empty average.
Do not compile; requires a return of type double
Why wrong: It will compile if a return is provided; returning 0.0 works.
Throw a RuntimeException
Why wrong: Not required; returning 0.0 is acceptable.
Return null
Why wrong: Return type is double, not Double; cannot return null.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Return 0.0
Option A is correct because the method should return 0.0 for an empty array to avoid division by zero and to provide a safe default value. In Java, an empty array has length 0, and computing the average would require dividing by zero, which throws an ArithmeticException. Returning 0.0 is a common convention for empty collections, as it allows the caller to handle the result gracefully without crashing.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
Return 0.0
Why this is correct
Default value for empty average.
Related concept
Read the scenario before looking for a memorised answer.
Do not compile; requires a return of type double
Why it's wrong here
It will compile if a return is provided; returning 0.0 works.
Throw a RuntimeException
Why it's wrong here
Not required; returning 0.0 is acceptable.
Return null
Why it's wrong here
Return type is double, not Double; cannot return null.
Common exam traps
Oracle often tests the distinction between primitive and wrapper types; the trap here is that candidates may think returning null is acceptable for a double return type, but double is a primitive and cannot hold null.
Detailed technical explanation
Under the hood, Java arrays are objects with a public final length field. When the array is empty, the loop to sum scores would execute zero times, and dividing the sum (0) by the length (0) would cause an integer division by zero, which throws an ArithmeticException. By returning 0.0 early, the method avoids this runtime exception and follows the principle of defensive programming. In real-world scenarios, such as grading systems, returning 0.0 for an empty test score array allows the application to display 'No scores' or a default value without crashing.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A practitioner preparing for the 1Z0-811 exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
What to study next
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FAQ
Arrays and Methods — This question tests Arrays and Methods — Read the scenario before looking for a memorised answer..
The correct answer is: Return 0.0 — Option A is correct because the method should return 0.0 for an empty array to avoid division by zero and to provide a safe default value. In Java, an empty array has length 0, and computing the average would require dividing by zero, which throws an ArithmeticException. Returning 0.0 is a common convention for empty collections, as it allows the caller to handle the result gracefully without crashing.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 30, 2026
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