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.
Which TWO are terminal operations on the Stream interface? (Choose two.)
count()
Terminal operation that returns the count of elements.
forEach()
Terminal operation that performs an action for each element.
filter()
Why wrong: Intermediate operation, returns a new stream.
map()
Why wrong: Intermediate operation, returns a new stream.
sorted()
Why wrong: Intermediate operation, returns a new stream.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
count()
A is correct because `count()` is a terminal operation that reduces the stream to a single `long` value by counting the number of elements after processing the pipeline. It triggers the stream pipeline execution and consumes the stream, making it a terminal operation per the `Stream` interface specification.
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.
count()
Why this is correct
Terminal operation that returns the count of elements.
Related concept
Read the scenario before looking for a memorised answer.
forEach()
Why this is correct
Terminal operation that performs an action for each element.
Related concept
Read the scenario before looking for a memorised answer.
filter()
Why it's wrong here
Intermediate operation, returns a new stream.
map()
Why it's wrong here
Intermediate operation, returns a new stream.
sorted()
Why it's wrong here
Intermediate operation, returns a new stream.
Common exam traps
The trap here is that candidates often confuse intermediate operations (like `filter`, `map`, `sorted`) with terminal operations because they are commonly chained together, but only terminal operations produce a non-stream result or side effect and close the stream.
Detailed technical explanation
Terminal operations like `count()` and `forEach()` trigger the lazy evaluation of the stream pipeline, executing all intermediate operations (e.g., `filter`, `map`) on each element. Under the hood, `count()` may optimize by short-circuiting or using spliterator characteristics (e.g., `SIZED`) to avoid processing all elements when possible. In real-world scenarios, using a terminal operation incorrectly can lead to `IllegalStateException` if the stream is reused, as streams are single-use pipelines.
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
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Working with Streams and Lambda Expressions — study guide chapter
Learn the concepts, then practise the questions
Working with Streams and Lambda Expressions practice questions
Targeted practice on this topic area only
All 1Z0-829 questions
509 questions across all exam domains
Oracle Certified Professional Java SE 17 Developer 1Z0-829 study guide
Full concept coverage aligned to exam objectives
1Z0-829 practice test guide
How to use practice tests most effectively before exam day
Related practice questions
Use these pages to review the topic behind this question. This is how one missed question becomes focused revision.
Practise 1Z0-829 questions linked to Handling Date, Time, Text, Numeric and Boolean Values.
Practise 1Z0-829 questions linked to Controlling Program Flow.
Practise 1Z0-829 questions linked to Utilizing Java Object-Oriented Approach.
Practise 1Z0-829 questions linked to Handling Exceptions.
Practise 1Z0-829 questions linked to Working with Arrays and Collections.
Practise 1Z0-829 questions linked to Working with Streams and Lambda Expressions.
Practise 1Z0-829 questions linked to Java Platform Overview and Packaging.
Practise 1Z0-829 questions linked to Java I/O API and Securing Applications.
Practise 1Z0-829 questions linked to 1Z0-829 fundamentals.
Practise 1Z0-829 questions linked to 1Z0-829 scenario.
Practise 1Z0-829 questions linked to 1Z0-829 troubleshooting.
Practice this exam
Short sessions build daily habit. Longer sessions build exam-day stamina. Try a timed session to simulate real conditions.
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: count() — A is correct because `count()` is a terminal operation that reduces the stream to a single `long` value by counting the number of elements after processing the pipeline. It triggers the stream pipeline execution and consumes the stream, making it a terminal operation per the `Stream` interface specification.
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.
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 →
Keep practising
Last reviewed: Jun 25, 2026
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.