The answer is Stream.generate(Math::random). This is correct because the generate method takes a Supplier functional interface and produces an unordered, infinite sequential stream by repeatedly invoking that supplier with no termination condition, making it ideal for creating infinite streams in Java 17. On the Oracle Certified Professional Java SE 17 Developer 1Z0-829 exam, this question tests your understanding of the Stream API’s infinite stream creation methods, specifically contrasting generate with iterate and the finite limit operation. A common trap is confusing generate with iterate: while both can produce infinite streams, iterate requires a seed and an optional predicate for finite generation, whereas generate simply calls the supplier forever. Remember that generate is for stateless, side-effect-free suppliers like Math::random, while iterate is for stateful, incremental sequences. Memory tip: think “generate gives you a never-ending supply from a single source” — no seed, no stop, just pure repetition.
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 THREE of the following are valid ways to create an infinite stream? (Choose three.)
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
IntStream.generate(() -> 0)
Option A is correct because `IntStream.generate(() -> 0)` uses a supplier that always returns 0, producing an infinite stream of zeros. The `generate` method creates an unordered infinite stream by repeatedly invoking the supplier, with no termination condition.
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.
✓
IntStream.generate(() -> 0)
Why this is correct
Generates an infinite IntStream of zeros.
Related concept
Read the scenario before looking for a memorised answer.
✓
Stream.iterate(1, n -> n+1)
Why this is correct
Creates an infinite sequential stream starting from 1, incrementing by 1.
Related concept
Read the scenario before looking for a memorised answer.
✗
IntStream.range(0, Integer.MAX_VALUE)
Why it's wrong here
This is a finite stream (though very large) because range excludes the end value.
✓
Stream.generate(Math::random)
Why this is correct
Generates an infinite stream via a Supplier.
Related concept
Read the scenario before looking for a memorised answer.
✗
Stream.of(1,2,3)
Why it's wrong here
This creates a finite stream with three elements.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates mistakenly think `IntStream.range(0, Integer.MAX_VALUE)` is infinite because the upper bound is large, but it is actually a finite stream that terminates after producing Integer.MAX_VALUE elements.
Detailed technical explanation
How to think about this question
Under the hood, `Stream.generate` and `Stream.iterate` produce infinite streams by relying on lazy evaluation; elements are computed on demand as the terminal operation pulls them. `IntStream.range` is a stateful, short-circuiting operation that precomputes the range and stops after the upper bound, making it inherently finite. In real-world scenarios, infinite streams are often used with `limit()` or `findFirst()` to avoid unbounded memory consumption.
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 small business has 20 workstations on the 192.168.1.0/24 network and one public IP from its ISP. The router uses PAT (NAT overload) so all 20 devices share one public address using different source ports. NAT questions test whether you understand the four address terms and which direction each translation applies.
What to study next
Got this wrong? Here's your next step.
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 — 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: IntStream.generate(() -> 0) — Option A is correct because `IntStream.generate(() -> 0)` uses a supplier that always returns 0, producing an infinite stream of zeros. The `generate` method creates an unordered infinite stream by repeatedly invoking the supplier, with no termination condition.
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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Question Discussion
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