Solve this multiple-choice question and choose the correct option.

Introduction / Context:This question tests knowledge of different Map implementations in Java and their ordering characteristics. Concept / Approach: HashMap → no ordering guarantee. TreeMap → natural or custom comparator order, not iteration order. LinkedHashMap → maintains insertion order or access order. Step-by-Step Reasoning: If you want the iteration order of an existing Map to be preserved, use LinkedHashMap and construct it with the existing Map. Why Other Options Are Wrong:TreeMap re-sorts keys, HashMap randomizes order, and "depends on implementation" is too vague. Final Answer:LinkedHashMap

Home » Java Programming » Objects and Collections

Java — Which Map implementation maintains iteration order of an existing Map?

Difficulty: Medium

TreeMap
HashMap
LinkedHashMap
The answer depends on the implementation of the existing instance.

Correct Answer: LinkedHashMap

Explanation:

Introduction / Context:This question tests knowledge of different Map implementations in Java and their ordering characteristics.

Concept / Approach:

HashMap → no ordering guarantee.
TreeMap → natural or custom comparator order, not iteration order.
LinkedHashMap → maintains insertion order or access order.

Step-by-Step Reasoning:

If you want the iteration order of an existing Map to be preserved, use LinkedHashMap and construct it with the existing Map.

Why Other Options Are Wrong:TreeMap re-sorts keys, HashMap randomizes order, and "depends on implementation" is too vague.

Java — Which Map implementation maintains iteration order of an existing Map?

More Questions from Objects and Collections

Discussion & Comments