1Z0-829 Working with Arrays and Collections Practice Question
This 1Z0-829 practice question tests your understanding of working with arrays and collections. 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 about the java.util.Collections class 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.synchronizedList(List) returns a synchronized list backed by the specified list.
Option D is correct because Collections.synchronizedList(List) returns a synchronized (thread-safe) list backed by the specified list. This method wraps the provided list in a synchronized wrapper, ensuring that all access to the underlying list is serialized when accessed through the returned list. It does not create a new independent list but provides a view that synchronizes all method calls.
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.sort(List) returns a new sorted list.
Why it's wrong here
Collections.sort sorts the list in place; it does not return a new list.
✗
Collections.reverse(List) returns a new reversed list.
Why it's wrong here
Collections.reverse reverses the order in place.
✗
Collections.shuffle(List) returns a new shuffled list.
Why it's wrong here
Collections.shuffle randomizes the list in place.
✓
Collections.synchronizedList(List) returns a synchronized list backed by the specified list.
Why this is correct
It returns a thread-safe list backed by the specified list.
Related concept
Read the scenario before looking for a memorised answer.
✓
Collections.unmodifiableList(List) returns an unmodifiable view of the specified list.
Why this is correct
It returns an unmodifiable view; any attempt to modify it throws UnsupportedOperationException.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse mutating methods like sort, reverse, and shuffle with methods that return new collections, when in fact these methods modify the list in place and return void, whereas synchronizedList and unmodifiableList return wrapper views.
Detailed technical explanation
How to think about this question
The Collections class provides static utility methods that operate on or return collections. The synchronizedList method uses a mutex (the wrapper list itself) to synchronize all method calls, but iteration over the returned list must still be synchronized externally by the caller to avoid ConcurrentModificationException. This is a common pitfall because the wrapper only synchronizes individual method calls, not compound operations like iteration.
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.synchronizedList(List) returns a synchronized list backed by the specified list. — Option D is correct because Collections.synchronizedList(List) returns a synchronized (thread-safe) list backed by the specified list. This method wraps the provided list in a synchronized wrapper, ensuring that all access to the underlying list is serialized when accessed through the returned list. It does not create a new independent list but provides a view that synchronizes all method calls.
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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