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.
Which TWO methods correctly modify the passed array in place?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
public void zeroOut(int[] a) { for (int i = 0; i < a.length; i++) a[i] = 0; }
Option A is correct because it directly modifies each element of the passed array by assigning 0 to a[i] within the loop. In Java, when an array is passed to a method, the method receives a reference to the same array object, so changes to the array's elements are reflected in the caller's array.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✓
public void zeroOut(int[] a) { for (int i = 0; i < a.length; i++) a[i] = 0; }
Why this is correct
Sets each element to 0, modifying the original array.
Related concept
Read the scenario before looking for a memorised answer.
✓
public void incrementEach(int[] a) { for (int i = 0; i < a.length; i++) a[i]++; }
Why this is correct
Modifies each element in place.
Related concept
Read the scenario before looking for a memorised answer.
✗
public void reset(int[] a) { a = new int[10]; }
Why it's wrong here
Creates a new array local to the method; original unchanged.
✗
public void swap(int[] a) { int[] temp = a; a = new int[1]; a[0] = temp[0]; }
Why it's wrong here
Reassigns the reference; original array unchanged.
✗
public void setFirst(int[][] a) { a = new int[1][1]; a[0][0] = 5; }
Why it's wrong here
Reassigns the reference, not modifying original.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the misconception that reassigning the method parameter (e.g., a = new int[10]) modifies the original array, when in fact it only changes the local reference, leaving the original array untouched.
Detailed technical explanation
How to think about this question
Java uses pass-by-value for all arguments, but for objects (including arrays), the value passed is a reference to the object. This means the method can modify the object's state (e.g., array elements) but cannot change which object the caller's variable refers to. This distinction is crucial when designing methods that mutate data structures, such as in-place sorting algorithms or buffer manipulation.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
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
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Arrays and Methods — This question tests Arrays and Methods — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: public void zeroOut(int[] a) { for (int i = 0; i < a.length; i++) a[i] = 0; } — Option A is correct because it directly modifies each element of the passed array by assigning 0 to a[i] within the loop. In Java, when an array is passed to a method, the method receives a reference to the same array object, so changes to the array's elements are reflected in the caller's array.
What should I do if I get this 1Z0-811 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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