The answer is `list.sort(Comparator.naturalOrder())` and `Collections.sort(list)`. Both methods sort a List<String> in natural ascending order because they rely on the elements’ implementation of the `Comparable` interface—`String` already defines natural ordering as lexicographic comparison based on Unicode values. `List.sort()` is a default method added in Java 8 that sorts the list in place using a provided comparator, while `Collections.sort()` is the classic utility method that internally calls `list.sort(null)` when no comparator is given, defaulting to natural order. On the Oracle Certified Professional Java SE 17 Developer 1Z0-829 exam, this distinction tests your understanding of the `List.sort()` API versus the legacy `Collections` approach, and a common trap is assuming `list.sort()` without an argument works—it requires a comparator, so `list.sort(null)` or `list.sort(Comparator.naturalOrder())` is needed. Memory tip: think “list dot sort needs a comparator; Collections dot sort defaults to natural.”
1Z0-829 Working with Arrays and Collections Practice Question
This 1Z0-829 practice question tests your understanding of working with arrays and collections. 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 of the following will sort a List<String> in natural (ascending) order?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
list.sort(Comparator.naturalOrder());
Option A is correct because `Comparator.naturalOrder()` returns a comparator that imposes the natural (ascending) ordering on `String` objects, which is lexicographic order based on Unicode values. The `List.sort()` method accepts this comparator and sorts the list in place, making it a concise and idiomatic way to sort a list in ascending order.
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.
✓
list.sort(Comparator.naturalOrder());
Why this is correct
Correct: naturalOrder comparator sorts in ascending order.
Related concept
Read the scenario before looking for a memorised answer.
✗
list.sort((a,b) -> b.compareTo(a));
Why it's wrong here
Incorrect: comparing b to a reverses the order, resulting in descending.
Incorrect: reverseOrder sorts in descending order.
✓
Collections.sort(list);
Why this is correct
Correct: Collections.sort sorts the list in natural order.
Related concept
Read the scenario before looking for a memorised answer.
✗
Arrays.sort(list);
Why it's wrong here
Incorrect: Arrays.sort does not accept a List; it works on arrays only.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse `Collections.sort(list)` (which sorts in natural order) with `Collections.sort(list, Collections.reverseOrder())` (which sorts in reverse order), and may also mistakenly think `Arrays.sort()` works on a `List` without realizing it requires an array.
Detailed technical explanation
How to think about this question
Under the hood, `Comparator.naturalOrder()` returns a comparator that delegates to `Comparable.compareTo()`, which for `String` uses lexicographic comparison based on Unicode code points. The `List.sort()` method, introduced in Java 8, sorts the list in place using `Arrays.sort()` internally after converting the list to an array, providing O(n log n) performance (TimSort). A subtle behavior is that `naturalOrder()` returns a comparator that throws `NullPointerException` if any element is null, unlike `Comparator.nullsFirst()` which can handle nulls gracefully.
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 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
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.
Working with Arrays and Collections — This question tests Working with Arrays and Collections — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: list.sort(Comparator.naturalOrder()); — Option A is correct because `Comparator.naturalOrder()` returns a comparator that imposes the natural (ascending) ordering on `String` objects, which is lexicographic order based on Unicode values. The `List.sort()` method accepts this comparator and sorts the list in place, making it a concise and idiomatic way to sort a list in ascending order.
What should I do if I get this 1Z0-829 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.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
This 1Z0-829 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 1Z0-829 exam.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.