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. 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.
Stream<String> stream = Stream.of("one", "two", "three", "four");
List<String> list = stream
.filter(s -> s.startsWith("t"))
.collect(Collectors.toList());
System.out.println(list);Refer to the exhibit. What is the output?
Stream<String> stream = Stream.of("one", "two", "three", "four");
List<String> list = stream
.filter(s -> s.startsWith("t"))
.collect(Collectors.toList());
System.out.println(list);[one, two, three, four]
Why wrong: Includes all strings.
[two]
Why wrong: Missing 'three'.
[two, three]
Filter with startsWith("t") keeps 'two' and 'three'.
[one, four]
Why wrong: Incorrect filter condition.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
[two, three]
The code uses `dropWhile` on a stream of strings, which drops elements from the stream as long as the predicate (string length < 5) is true. Once the predicate becomes false (for "three", length 5), it stops dropping and includes all remaining elements. The stream then skips the first element with `skip(1)`, resulting in ["two", "three"].
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.
[one, two, three, four]
Why it's wrong here
Includes all strings.
[two]
Why it's wrong here
Missing 'three'.
[two, three]
Why this is correct
Filter with startsWith("t") keeps 'two' and 'three'.
Related concept
Read the scenario before looking for a memorised answer.
[one, four]
Why it's wrong here
Incorrect filter condition.
Common exam traps
The trap here is confusing `dropWhile` with `filter` — candidates often think `dropWhile` removes all elements matching the predicate, but it only removes the leading prefix until the first non-match, then includes everything after.
Detailed technical explanation
`dropWhile` is a stateful intermediate operation that short-circuits once the predicate fails, unlike `filter` which evaluates every element. Under the hood, it uses a spliterator that transitions from a dropping state to a taking state. This is particularly useful in ordered streams where you want to discard a prefix of elements based on a condition, such as skipping log entries before a certain timestamp.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
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. 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
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FAQ
Working with Streams and Lambda Expressions — This question tests Working with Streams and Lambda Expressions — Read the scenario before looking for a memorised answer..
The correct answer is: [two, three] — The code uses `dropWhile` on a stream of strings, which drops elements from the stream as long as the predicate (string length < 5) is true. Once the predicate becomes false (for "three", length 5), it stops dropping and includes all remaining elements. The stream then skips the first element with `skip(1)`, resulting in ["two", "three"].
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: Jul 4, 2026
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