Quick Answer
The answer is the invocation `process(new int[]{1, 2})` because it creates an ambiguity between the two overloaded methods. This occurs because Java treats varargs (`int... a`) as an array parameter at the bytecode level, so when you pass an explicit `int[]` object, both the fixed-array method and the varargs method match the argument exactly. The compiler cannot decide which one to call, resulting in a compilation error. On the Oracle Java Foundations 1Z0-811 exam, this question tests your understanding of method resolution and the subtle conflict between array parameters and varargs when the argument is itself an array. A common trap is assuming varargs always has lower priority, but when the argument is already an array, the compiler sees two equally valid matches. To remember this, think: "An array in the call, ambiguity for all."
This 1Z0-811 practice question tests your understanding of arrays and methods. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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.
Which method invocation is ambiguous given these overloaded methods? public void process(int[] a) and public void process(int... a)
process(1, 2);
Why wrong: Only varargs matches (int...).
process((int[]) null);
Why wrong: Explicit cast to int[] resolves to the array version.
process();
Why wrong: Only varargs matches (empty arguments).
process(new int[]{1, 2});
Both methods accept an int array, causing ambiguity.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
process(new int[]{1, 2});
Option D is correct because when you call process(new int[]{1, 2}), the compiler cannot determine whether to use the method with an int[] parameter or the varargs method (int... a). Both methods have the same signature after type erasure, and the argument is an int array, which matches both exactly, causing an ambiguity error.
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.
process(1, 2);
Why it's wrong here
Only varargs matches (int...).
process((int[]) null);
Why it's wrong here
Explicit cast to int[] resolves to the array version.
process();
Why it's wrong here
Only varargs matches (empty arguments).
process(new int[]{1, 2});
Why this is correct
Both methods accept an int array, causing ambiguity.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
The trap here is that candidates think varargs and array parameters are distinct, but they are not; the compiler treats them as identical when the argument is an array, leading to ambiguity.
Detailed technical explanation
Under the hood, varargs (int... a) is syntactic sugar for an array parameter (int[] a), and both methods compile to the same bytecode signature. The Java Language Specification (JLS §15.12.2) states that when both methods are applicable, the compiler must choose the most specific one; if neither is more specific, the invocation is ambiguous and causes a compile-time error. This ambiguity occurs only when the argument is explicitly an int array, as in D.
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.
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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: process(new int[]{1, 2}); — Option D is correct because when you call process(new int[]{1, 2}), the compiler cannot determine whether to use the method with an int[] parameter or the varargs method (int... a). Both methods have the same signature after type erasure, and the argument is an int array, which matches both exactly, causing an ambiguity error.
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 25, 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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