Obtain Index of a Given LinkedHashSet Element Without Iteration

LinkedHashSet maintains uniqueness and order but lacks efficient index-based lookups (O(n) time). Several approaches exist: direct iteration, converting to List/array (still O(n) for indexOf), maintaining separate List+Set structures, or building a custom implementation with dual maps for O(1) lookups. The custom approach with element-to-index and index-to-element maps offers the best performance for frequent index queries, though removal requires reindexing (O(n)). Choice depends on operation frequency, dataset size, and whether you prioritize additions, removals, or lookups. Thread safety requires synchronization when coordinating multiple data structures.