Which Java collection lets you associate elements with keys while iterating in insertion (FIFO) order?

Introduction / Context:Different Java collections provide different ordering guarantees. The question asks for a map (key–value association) that also preserves insertion order, enabling FIFO-style iteration.

Given Data / Assumptions:

• We need key–value association (i.e., a Map).
• We want predictable iteration order: specifically insertion order (FIFO-like).

Concept / Approach:LinkedHashMap combines a hash table with a doubly-linked list to maintain predictable iteration order. By default, it preserves insertion order; alternatively, it can be configured for access order. Other map implementations either do not preserve order (HashMap) or impose a sort order by key (TreeMap), not insertion order.

Step-by-Step Reasoning:

Verification / Alternative check:Quick test inserting keys A, B, C into a LinkedHashMap and iterating shows A, B, C order.

Why Other Options Are Wrong:ArrayList lacks keys; HashMap is unordered; TreeMap orders by key comparator; PriorityQueue is a heap, not key–value store.

Common Pitfalls:Confusing insertion order with sorted order; assuming HashMap iteration order is stable (it is not guaranteed).

Final Answer:java.util.LinkedHashMap