How Can I Implement a Java Map That Preserves Insertion Order?

Implementing Map with Insertion Order Maintenance in Java

Many Java developers find themselves in need of a class that maintains key-value associations while preserving the insertion order, unlike the traditional HashMap class.

Existing Approach

The initial approach involves using a Hashtable, extracting an iterator, and iterating through values to manipulate them. However, this method lacks control over the retrieval order.

Suggested Solution

To address this issue, two potential solutions are available:

• LinkedHashMap: Maintains insertion order while allowing quick retrieval of values.
• TreeMap: Preserves order but requires a Comparator or natural ordering for keys.

LinkedHashMap exhibits O(1) complexity for operations like containsKey, get, put, and remove, while TreeMap operates at O(log n) for these actions.

Alternative:

For cases where a predictable sort order is sufficient, the interfaces NavigableMap and SortedMap can be employed, allowing for greater flexibility and decoupling from specific implementations.

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