1Z0-829 Working with Arrays and Collections Practice Question
This 1Z0-829 practice question tests your understanding of working with arrays and collections. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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 of the following statements about the Collections framework are true?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Collections.unmodifiableList returns an unmodifiable view of the list.
Option B is correct because `Collections.unmodifiableList()` returns a view of the specified list that cannot be modified. Any attempt to modify the returned list (e.g., add, remove, set) will throw an `UnsupportedOperationException`. This is a standard method in the Java Collections Framework to provide read-only access to a list.
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.
✗
Collections.checkedList performs type checking at compile time.
Why it's wrong here
Incorrect: checkedList performs runtime type checking when elements are added.
✓
Collections.unmodifiableList returns an unmodifiable view of the list.
Why this is correct
Correct: it wraps the list to prevent modifications.
Related concept
Read the scenario before looking for a memorised answer.
✗
List.of returns a mutable list.
Why it's wrong here
Incorrect: List.of returns an immutable list; any modification throws UnsupportedOperationException.
✓
Collections.synchronizedList returns a thread-safe list.
Why this is correct
Correct: it synchronizes all methods to ensure thread safety.
Related concept
Read the scenario before looking for a memorised answer.
✗
Arrays.asList returns a mutable list of variable size.
Why it's wrong here
Incorrect: the list is mutable but fixed-size; add/remove throw UnsupportedOperationException.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse `Collections.unmodifiableList()` with `List.of()` or assume that `Arrays.asList()` returns a fully mutable list of variable size, when in fact it returns a fixed-size list backed by the array.
Detailed technical explanation
How to think about this question
Under the hood, `Collections.unmodifiableList()` wraps the original list in an inner class that delegates all read operations to the backing list but overrides mutator methods to throw `UnsupportedOperationException`. This is a classic example of the Decorator pattern. A subtle behavior is that the returned view is still backed by the original list, so changes to the original list are reflected in the unmodifiable view, which can lead to unexpected side effects if the original list is later modified.
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.
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 Arrays and Collections — This question tests Working with Arrays and Collections — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Collections.unmodifiableList returns an unmodifiable view of the list. — Option B is correct because `Collections.unmodifiableList()` returns a view of the specified list that cannot be modified. Any attempt to modify the returned list (e.g., add, remove, set) will throw an `UnsupportedOperationException`. This is a standard method in the Java Collections Framework to provide read-only access to a list.
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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