Quick Answer
The answer is 18. This result comes from a three-step stream pipeline calculation: the filter method first selects only the even numbers from the stream, then mapToInt transforms each remaining element by multiplying by 3, and finally sum adds those transformed values together. In this specific case, the even numbers 2 and 4 pass through the filter, become 6 and 12 after the mapToInt operation, and their sum is 18. On the Oracle Certified Professional Java SE 17 Developer 1Z0-829 exam, this pattern tests your understanding of intermediate operations like filter and mapToInt, which are lazy until a terminal operation like sum triggers execution. A common trap is forgetting that filter runs before mapToInt in the pipeline order, so only elements that survive the filter are mapped and summed. Remember the mnemonic "Filter first, then map, then sum" to keep the pipeline sequence straight.
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.
Refer to the exhibit.
```java
List<Integer> numbers = Arrays.asList(2, 3, 4, 5);
int result = numbers.stream()
.filter(n -> n % 2 == 0)
.mapToInt(n -> n * 3)
.sum();
System.out.println(result);
```What is the output of the code above?
Refer to the exhibit.
```java
List<Integer> numbers = Arrays.asList(2, 3, 4, 5);
int result = numbers.stream()
.filter(n -> n % 2 == 0)
.mapToInt(n -> n * 3)
.sum();
System.out.println(result);
```18
Correct: (2*3)+(4*3)=6+12=18.
15
Why wrong: Incorrect: Might have forgotten filter.
9
Why wrong: Incorrect: That would be sum of 2+3+4? No.
27
Why wrong: Incorrect: If all numbers were processed: (2+3+4+5)*3=42? No.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
18
The filter keeps only even numbers: 2 and 4. mapToInt multiplies by 3: 6 and 12. Sum = 18.
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.
18
Why this is correct
Correct: (2*3)+(4*3)=6+12=18.
Related concept
Read the scenario before looking for a memorised answer.
15
Why it's wrong here
Incorrect: Might have forgotten filter.
9
Why it's wrong here
Incorrect: That would be sum of 2+3+4? No.
27
Why it's wrong here
Incorrect: If all numbers were processed: (2+3+4+5)*3=42? No.
Common exam traps
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
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.
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 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
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: 18 — The filter keeps only even numbers: 2 and 4. mapToInt multiplies by 3: 6 and 12. Sum = 18.
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.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 24, 2026
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