- A
B and C both produce Optional<Integer>.
Both B and C compile and produce an Optional<Integer> with the maximum element.
- B
list.stream().collect(Collectors.maxBy(Integer::compareTo))
Why wrong: This is also correct, but not the only one.
- C
list.stream().max()
Why wrong: max() without a Comparator does not compile; Stream.max() requires a Comparator argument.
- D
list.stream().max(Integer::compareTo)
Why wrong: This is correct, but is not the only correct answer.
Question 147 of 519
1Z0-829 Stream.max(Comparator) Practice Question
This 1Z0-829 practice question tests your understanding of working with streams and lambda expressions. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. A key principle to apply: stream.max(Comparator). 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 code will successfully produce an Optional<Integer> that contains the maximum value from a list of integers?
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
B and C both produce Optional<Integer>.
Options B and D both successfully produce an Optional<Integer> containing the maximum value. Option B uses Collectors.maxBy with a comparator, returning an Optional. Option D uses Stream.max(Integer::compareTo), which is valid and returns an Optional. Option A is incorrect because claims B and C produce Optional<Integer>, but C does not compile since Stream.max() requires a Comparator, and it also omits the valid D. Option C is invalid because Stream.max() without arguments does not exist.
Key principle: Stream.max(Comparator)
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
B and C both produce Optional<Integer>.
Why this is correct
Both B and C compile and produce an Optional<Integer> with the maximum element.
Related concept
Stream.max(Comparator)
- ✗
list.stream().collect(Collectors.maxBy(Integer::compareTo))
Why it's wrong here
This is also correct, but not the only one.
- ✗
list.stream().max()
Why it's wrong here
max() without a Comparator does not compile; Stream.max() requires a Comparator argument.
- ✗
list.stream().max(Integer::compareTo)
Why it's wrong here
This is correct, but is not the only correct answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Oracle tests that Stream.max(Comparator) and Collectors.maxBy(Comparator) both return Optional<T>. Also, calling max() without a Comparator on a Stream<T> does not compile; this is distinct from IntStream.max().
Detailed technical explanation
How to think about this question
The max() method on a Stream<T> is a terminal operation that returns an Optional<T> describing the maximum element according to the provided Comparator, or natural ordering if no comparator is given. Under the hood, it uses a reduction operation that compares elements pairwise, leveraging the Comparator's compare method. A common subtlety is that max() on an IntStream returns OptionalInt, not Optional<Integer>, which can cause type mismatch errors if not unboxed correctly. In real-world scenarios, using Collectors.maxBy is often preferred for readability and when combining with other collectors in a downstream operation.
KKey Concepts to Remember
- Stream.max(Comparator)
- Collectors.maxBy(Comparator)
- Optional<Integer>
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
Stream.max(Comparator)
Real-world example
How this comes up in practice
A practitioner preparing for the 1Z0-829 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. Stream.max(Comparator) 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
Questions learners often ask
What does this 1Z0-829 question test?
Working with Streams and Lambda Expressions — This question tests Working with Streams and Lambda Expressions — Stream.max(Comparator).
What is the correct answer to this question?
The correct answer is: B and C both produce Optional<Integer>. — Options B and D both successfully produce an Optional<Integer> containing the maximum value. Option B uses Collectors.maxBy with a comparator, returning an Optional. Option D uses Stream.max(Integer::compareTo), which is valid and returns an Optional. Option A is incorrect because claims B and C produce Optional<Integer>, but C does not compile since Stream.max() requires a Comparator, and it also omits the valid D. Option C is invalid because Stream.max() without arguments does not exist.
What should I do if I get this 1Z0-829 question wrong?
Review stream.max(Comparator), then practise related 1Z0-829 questions on the same topic to reinforce the concept.
What is the key concept behind this question?
Stream.max(Comparator)
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Last reviewed: Jun 30, 2026
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