The correct statements are A and B, along with the fact that a lambda expression can access final or effectively final local variables. This is true because lambdas are designed to work with functional interfaces—interfaces with a single abstract method—and when a lambda is assigned to such an interface variable, it provides the implementation for that method, making option A valid. Option B is correct because lambdas capture local variables from their enclosing scope, and to prevent concurrency issues, those variables must be final or effectively final (not reassigned after initialization). On the Oracle Certified Professional Java SE 17 Developer 1Z0-829 exam, this topic tests your understanding of lambda restrictions, often appearing in multiple-choice questions where common traps include assuming lambdas can throw any checked exception (they cannot unless the functional interface’s method declares it) or that they can implement multiple abstract methods (they cannot, as that would violate the functional interface contract). A helpful memory tip: “Lambdas love final—if it changes, it’s out of range.”
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 statements about lambda expressions are true? (Choose three.)
A. A lambda expression can be assigned to a functional interface variable.
B. A lambda expression can access final or effectively final local variables.
C. A lambda expression can throw any checked exception.
D. A lambda expression can be used to create an instance of an abstract class.
E. A lambda expression can be used to implement multiple abstract methods.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
A lambda expression can throw any checked exception.
Option A is correct because a lambda expression can be assigned to a variable of a functional interface type. The lambda provides the implementation for the single abstract method of that interface, and the assignment is valid as long as the lambda's parameter types and return type match the method signature.
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.
✓
A lambda expression can throw any checked exception.
Why this is correct
Correct if the functional interface's abstract method declares it.
Related concept
Read the scenario before looking for a memorised answer.
✓
A lambda expression can be assigned to a functional interface variable.
Why this is correct
Correct.
Related concept
Read the scenario before looking for a memorised answer.
✓
A lambda expression can access final or effectively final local variables.
Why this is correct
Correct.
Related concept
Read the scenario before looking for a memorised answer.
✗
A lambda expression can be used to implement multiple abstract methods.
Why it's wrong here
Only one abstract method.
✗
A lambda expression can be used to create an instance of an abstract class.
Why it's wrong here
Lambdas are for interfaces only.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates confuse the ability to assign a lambda to a functional interface variable (true) with the ability to implement multiple abstract methods (false), or they mistakenly think lambdas can instantiate abstract classes, which is not supported.
Detailed technical explanation
How to think about this question
Under the hood, the Java compiler translates a lambda expression into a synthetic method (via invokedynamic) that implements the functional interface's single abstract method. The lambda's body must be compatible with the method's throws clause; if the functional interface method does not declare a checked exception, the lambda cannot throw that checked exception. This is why Option C (in the original question) is correct: lambdas can only access final or effectively final local variables, a rule enforced by the compiler to prevent concurrency issues with variable capture.
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: A lambda expression can throw any checked exception. — Option A is correct because a lambda expression can be assigned to a variable of a functional interface type. The lambda provides the implementation for the single abstract method of that interface, and the assignment is valid as long as the lambda's parameter types and return type match the method signature.
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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