- A
The Stream API does not modify the original data source.
Streams operate on a view of the data; they do not modify the underlying collection or array.
- B
Lambda expressions can capture variables that are effectively final.
Lambda expressions can capture local variables that are effectively final, meaning they are not reassigned after initialization.
- C
A stream can be consumed by multiple terminal operations sequentially.
Why wrong: A stream can have at most one terminal operation; after that, the stream is consumed and cannot be used again.
- D
Intermediate operations on a stream are executed eagerly.
Why wrong: Intermediate operations are lazy; they are not executed until a terminal operation is invoked.
- E
Lambda expressions introduce a new level of scope, similar to an anonymous inner class.
Why wrong: Lambda expressions do not introduce a new scope; they share the scope with the enclosing method, so variables from the outer scope are accessible directly.
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.
Which TWO statements are true about the Stream API and lambda expressions in Java 17?
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
The Stream API does not modify the original data source.
Option A is correct because the Stream API is designed to work on a view of the data, not the data itself. Operations like filter, map, and collect produce new streams or results without altering the original collection, array, or I/O source. This non-interference guarantee is a core principle of the Stream API, ensuring safe parallel execution and functional programming style.
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.
- ✓
The Stream API does not modify the original data source.
Why this is correct
Streams operate on a view of the data; they do not modify the underlying collection or array.
Related concept
Read the scenario before looking for a memorised answer.
- ✓
Lambda expressions can capture variables that are effectively final.
Why this is correct
Lambda expressions can capture local variables that are effectively final, meaning they are not reassigned after initialization.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
A stream can be consumed by multiple terminal operations sequentially.
Why it's wrong here
A stream can have at most one terminal operation; after that, the stream is consumed and cannot be used again.
- ✗
Intermediate operations on a stream are executed eagerly.
Why it's wrong here
Intermediate operations are lazy; they are not executed until a terminal operation is invoked.
- ✗
Lambda expressions introduce a new level of scope, similar to an anonymous inner class.
Why it's wrong here
Lambda expressions do not introduce a new scope; they share the scope with the enclosing method, so variables from the outer scope are accessible directly.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse the lazy evaluation of intermediate operations with eager execution, or mistakenly believe a stream can be reused after a terminal operation, leading them to select options C or D.
Detailed technical explanation
How to think about this question
Under the hood, the Stream API uses internal iteration and a pipeline architecture where intermediate operations are combined into a single pass during the terminal operation. The effectively final requirement for captured variables in lambdas is enforced by the compiler to prevent race conditions in parallel streams; a variable is effectively final if its value does not change after initialization, even if not declared with the final keyword. In real-world scenarios, this prevents subtle bugs when streams are parallelized, as mutable captured variables would cause data inconsistency.
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.
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
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.
Quick reference
Cloud Service Model Comparison
| Model | You Manage | Provider Manages | Examples |
|---|---|---|---|
| IaaS | OS, runtime, apps, data | Hardware, hypervisor, networking | EC2, Azure VMs, GCP Compute Engine |
| PaaS | Apps and data | OS, runtime, middleware, hardware | Elastic Beanstalk, Azure App Service |
| SaaS | Data and settings only | Everything else | Microsoft 365, Salesforce, Workday |
| FaaS / Serverless | Function code only | Infra, scaling, runtime | Lambda, Azure Functions, Cloud Run |
| CaaS | Containers and apps | Kubernetes, OS, hardware | EKS, AKS, GKE |
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 — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The Stream API does not modify the original data source. — Option A is correct because the Stream API is designed to work on a view of the data, not the data itself. Operations like filter, map, and collect produce new streams or results without altering the original collection, array, or I/O source. This non-interference guarantee is a core principle of the Stream API, ensuring safe parallel execution and functional programming style.
What should I do if I get this 1Z0-829 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 11, 2026
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