- A
orders.stream().filter(o->o.getStatus().equals("PENDING")).sorted(Comparator.comparing(Order::getDate)).collect(Collectors.toSet())
Why wrong: A is wrong: collects Order objects instead of IDs.
- B
orders.stream().filter(o->o.getStatus().equals("PENDING")).map(Order::getId).sorted().collect(Collectors.toSet())
Why wrong: C is wrong: sorts IDs lexicographically, not by date.
- C
orders.stream().sorted(Comparator.comparing(Order::getDate)).filter(o->o.getStatus().equals("PENDING")).map(Order::getId).collect(Collectors.toSet())
Why wrong: D is wrong: sorts all orders before filtering, which is less efficient and changes behavior if order is not preserved.
- D
orders.stream().filter(o->o.getStatus().equals("PENDING")).sorted(Comparator.comparing(Order::getDate)).map(Order::getId).collect(Collectors.toSet())
B is correct: filters, sorts by date, maps to ID, collects to Set.
Quick Answer
The correct answer is the pipeline that applies filter, then sorted, then map, then collect in that exact order. This sequence is correct because it first reduces the data set by keeping only pending orders, then sorts those filtered orders by date, then transforms each Order into its ID, and finally collects those IDs into a Set. On the Oracle Certified Professional Java SE 17 Developer 1Z0-829 exam, this question tests your understanding of stream pipeline order and the principle that intermediate operations are lazy and execute in the order they appear, so filtering early minimizes the work for subsequent operations. A common trap is sorting before filtering, which wastes CPU cycles on orders that will be discarded, or mapping before sorting, which would sort by ID instead of by date. To remember the correct stream pipeline order, use the mnemonic “Filter First, Then Sort, Map, and Collect” — think of it as preparing your data before transforming and gathering it.
1Z0-829 Working with Streams and Lambda Expressions 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. 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.
A developer is refactoring a legacy codebase to use streams. The original code iterates over a list of 'Order' objects, filters orders with status 'PENDING', sorts them by date, and collects the order IDs into a set. Which stream pipeline correctly replaces this logic?
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
orders.stream().filter(o->o.getStatus().equals("PENDING")).sorted(Comparator.comparing(Order::getDate)).map(Order::getId).collect(Collectors.toSet())
Option B is correct because it filters pending orders, sorts by date, then maps to IDs and collects to a set. Option A is wrong because it collects Order objects instead of IDs. Option C is wrong because it sorts IDs, not dates. Option D is wrong because it sorts all orders before filtering, which is less efficient and may not match the original behavior.
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.
- ✗
orders.stream().filter(o->o.getStatus().equals("PENDING")).sorted(Comparator.comparing(Order::getDate)).collect(Collectors.toSet())
Why it's wrong here
A is wrong: collects Order objects instead of IDs.
- ✗
orders.stream().filter(o->o.getStatus().equals("PENDING")).map(Order::getId).sorted().collect(Collectors.toSet())
Why it's wrong here
C is wrong: sorts IDs lexicographically, not by date.
- ✗
orders.stream().sorted(Comparator.comparing(Order::getDate)).filter(o->o.getStatus().equals("PENDING")).map(Order::getId).collect(Collectors.toSet())
Why it's wrong here
D is wrong: sorts all orders before filtering, which is less efficient and changes behavior if order is not preserved.
- ✓
orders.stream().filter(o->o.getStatus().equals("PENDING")).sorted(Comparator.comparing(Order::getDate)).map(Order::getId).collect(Collectors.toSet())
Why this is correct
B is correct: filters, sorts by date, maps to ID, collects to Set.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Many certification questions include familiar terms but test a specific constraint. Read the exact wording before choosing an answer that is generally true but wrong for this case.
Detailed technical explanation
How to think about this question
This question should be treated as a scenario, not a definition check. Identify the problem, the constraint and the best action. Then compare each option against those facts.
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.
- Use explanations to understand the rule behind the answer.
TExam Day Tips
- Underline the problem statement mentally.
- 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 1Z0-829 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
Got this wrong? Here's your next step.
Identify which 1Z0-829 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
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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 — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: orders.stream().filter(o->o.getStatus().equals("PENDING")).sorted(Comparator.comparing(Order::getDate)).map(Order::getId).collect(Collectors.toSet()) — Option B is correct because it filters pending orders, sorts by date, then maps to IDs and collects to a set. Option A is wrong because it collects Order objects instead of IDs. Option C is wrong because it sorts IDs, not dates. Option D is wrong because it sorts all orders before filtering, which is less efficient and may not match the original behavior.
What should I do if I get this 1Z0-829 question wrong?
Identify which 1Z0-829 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 24, 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.
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