The answer is to pass `Arrays.asList(1,2,3)` into the `new ArrayList<Integer>()` constructor. This works because `Arrays.asList()` returns a fixed-size `List<Integer>` backed by the original array, but wrapping it in the `ArrayList` constructor creates a fully mutable, resizable `ArrayList<Integer>` containing the same elements. On the Oracle Certified Professional Java SE 17 Developer 1Z0-829 exam, this pattern tests your understanding of the difference between fixed-size lists and dynamic `ArrayList` objects—a common trap is assuming `Arrays.asList()` alone gives you a mutable `ArrayList`, when in fact it does not support structural modifications like `add()` or `remove()`. The exam frequently asks about valid ways to create an `ArrayList<Integer>`, and this constructor-based approach is a standard initialization technique for known values. Memory tip: think of `Arrays.asList()` as a "bridge" that needs the `ArrayList` constructor to become fully flexible—just like a fixed bridge needs a movable joint to expand.
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 THREE of the following are valid ways to create a new ArrayList<Integer>? (Select three.)
Creates an ArrayList from the List returned by Arrays.asList.
B
new ArrayList<>(10, 20, 30)
Why wrong: No constructor takes varargs of elements; this is invalid syntax.
C
new ArrayList<>(List.of(1,2,3))
Creates an ArrayList with elements 1,2,3 from an immutable list.
D
(ArrayList<Integer>) Arrays.asList(1,2,3)
Why wrong: Casting to ArrayList fails at runtime because Arrays.asList returns a java.util.Arrays.ArrayList (a private inner class) not java.util.ArrayList.
E
new ArrayList<Integer>() with initial capacity 10
Creates an empty ArrayList with initial capacity 10.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
new ArrayList<>(Arrays.asList(1,2,3))
Option A is correct because `Arrays.asList(1,2,3)` returns a fixed-size `List<Integer>`, and passing it to the `ArrayList` constructor creates a new, mutable `ArrayList<Integer>` containing the same elements. This is a standard way to initialize an `ArrayList` with known values.
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.
✓
new ArrayList<>(Arrays.asList(1,2,3))
Why this is correct
Creates an ArrayList from the List returned by Arrays.asList.
Related concept
Read the scenario before looking for a memorised answer.
✗
new ArrayList<>(10, 20, 30)
Why it's wrong here
No constructor takes varargs of elements; this is invalid syntax.
✓
new ArrayList<>(List.of(1,2,3))
Why this is correct
Creates an ArrayList with elements 1,2,3 from an immutable list.
Related concept
Read the scenario before looking for a memorised answer.
✗
(ArrayList<Integer>) Arrays.asList(1,2,3)
Why it's wrong here
Casting to ArrayList fails at runtime because Arrays.asList returns a java.util.Arrays.ArrayList (a private inner class) not java.util.ArrayList.
✓
new ArrayList<Integer>() with initial capacity 10
Why this is correct
Creates an empty ArrayList with initial capacity 10.
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 confuse `Arrays.asList` with `ArrayList` and attempt to cast the returned list directly, not realizing it is a different class that cannot be cast to `ArrayList`.
Detailed technical explanation
How to think about this question
The `ArrayList` constructor that accepts a `Collection` copies the elements into a new internal `Object[]` array, ensuring full mutability. `Arrays.asList` returns a fixed-size list backed by the original array, so modifications like `add` or `remove` are unsupported, but passing it to the `ArrayList` constructor bypasses this limitation. Option E is valid because `new ArrayList<Integer>(10)` sets the initial capacity to 10, which is a legal constructor call, though it creates an empty list.
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: new ArrayList<>(Arrays.asList(1,2,3)) — Option A is correct because `Arrays.asList(1,2,3)` returns a fixed-size `List<Integer>`, and passing it to the `ArrayList` constructor creates a new, mutable `ArrayList<Integer>` containing the same elements. This is a standard way to initialize an `ArrayList` with known values.
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.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
This 1Z0-829 practice question is part of Courseiva's free Oracle certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the 1Z0-829 exam.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.