1Z0-829 Working with Streams and Lambda Expressions Practice Question
Which TWO statements are true about the Stream API and lambda expressions in Java 17?
⚠ Common exam trap
It's easy for candidates to 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.
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.
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.
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.
- ✓
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.
- ✗
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.
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 |
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