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Concepts
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Resizable array
Doubly linked list
Hash table
Red-black tree
Hash table with buckets
Question 124 of 513
1Z0-829 Working with Arrays and Collections Practice Question
Match each Java collection class to its underlying data structure.
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
✓
ArrayList: Resizable array
ArrayList uses a resizable array; LinkedList uses a doubly linked list; HashSet uses a hash table; TreeSet uses a red-black tree. Common confusions involve mixing up TreeMap with ArrayList or HashMap with TreeMap.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
ArrayList: Resizable array
Why this is correct
ArrayList internally uses a resizable array to store elements.
- ✓
LinkedList: Doubly linked list
Why this is correct
LinkedList is implemented as a doubly linked list, allowing efficient insertions/deletions.
- ✓
HashSet: Hash table
Why this is correct
HashSet uses a hash table (backed by HashMap) for constant-time operations.
- ✓
TreeSet: Red-black tree
Why this is correct
TreeSet is based on a red-black tree, maintaining sorted order.
- ✗
HashMap: Red-black tree
Why it's wrong here
Incorrect — HashMap uses a hash table, not a red-black tree. Red-black tree is used by TreeMap.
- ✗
TreeMap: Resizable array
Why it's wrong here
Incorrect — TreeMap uses a red-black tree, not a resizable array. Resizable array is for ArrayList.
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Last reviewed: Jun 11, 2026
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.
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