Quick Answer
The correct method signature is public int[] doubleArray(int[] input) because the return type must be an array of integers to send back a new array with each element doubled, and the parameter must be an int[] to accept the original input array. In Java, when a method returns an array, the return type in the signature must include square brackets after the data type, just as the parameter type does for the incoming array. On the Oracle Java Foundations 1Z0-811 exam, this question tests your understanding of array references as return types and parameters, a common topic in method declaration questions. A frequent trap is confusing the return type with a primitive int or forgetting the brackets entirely, which would prevent the method from returning the new array object. To remember, think of the signature as a mirror: both the input and output are arrays, so both sides of the method declaration must use the same bracket notation. A helpful mnemonic is "brackets on both sides for array rides."
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 needed to return a new array where each element is doubled. Which method signature correctly accomplishes this?
public int doubleArray(int[] input)
Why wrong: Return type int does not match expected output array.
public int[] doubleArray(int[] input)
Correct return type and parameter.
public int[] doubleArray(int input)
Why wrong: Parameter type should be int[] to receive an array.
public void doubleArray(int[] input)
Why wrong: Void return type does not return the new array.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
public int[] doubleArray(int[] input)
Option B is correct because the method must return a new array with doubled values, so the return type must be `int[]` (an array of integers) and the parameter must be an `int[]` (the input array). This signature allows the method to accept an array, process each element, and return a new array of the same length with each element doubled.
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.
public int doubleArray(int[] input)
Why it's wrong here
Return type int does not match expected output array.
public int[] doubleArray(int[] input)
Why this is correct
Correct return type and parameter.
Related concept
Read the scenario before looking for a memorised answer.
public int[] doubleArray(int input)
Why it's wrong here
Parameter type should be int[] to receive an array.
public void doubleArray(int[] input)
Why it's wrong here
Void return type does not return the new array.
Common exam traps
Oracle often tests the distinction between returning a single value versus an array, and candidates may confuse the return type `int` with `int[]` or forget that the parameter must match the array type to process multiple elements.
Trap categories for this question
Command / output trap
Return type int does not match expected output array.
Detailed technical explanation
In Java, arrays are objects, and the method signature must reflect that the return type is an array reference (`int[]`). When doubling each element, a new array is typically created using `new int[input.length]` and populated in a loop, leaving the original array unchanged. This is a common pattern for immutable transformations, ensuring the caller's data is not modified.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A small business has 20 workstations on the 192.168.1.0/24 network and one public IP from its ISP. The router uses PAT (NAT overload) so all 20 devices share one public address using different source ports. NAT questions test whether you understand the four address terms and which direction each translation applies.
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: public int[] doubleArray(int[] input) — Option B is correct because the method must return a new array with doubled values, so the return type must be `int[]` (an array of integers) and the parameter must be an `int[]` (the input array). This signature allows the method to accept an array, process each element, and return a new array of the same length with each element doubled.
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
This 1Z0-811 practice question is part of Courseiva's free Oracle certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the 1Z0-811 exam.
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