HashMap vs. Hashtable in Java: Which Data Structure Should You Choose?

Comparing HashMap and Hashtable in Java

When storing key-value pairs in Java, developers often contemplate the choice between HashMap and Hashtable. While both serve as data structures for mapping keys to values, they differ in several key aspects.

Key Differences

• Synchronization: Hashtable is synchronized, meaning that its methods are thread-safe. HashMap, on the other hand, is unsynchronized, offering better performance for non-threaded applications.
• Null Values and Keys: Hashtable prohibits null keys or values. HashMap, however, permits one null key and multiple null values.
• Iteration Order: Unlike HashMap, Hashtable does not provide guaranteed iteration order. For predictable iteration based on insertion order, utilize LinkedHashMap, a HashMap subclass.

Efficiency for Non-Threaded Applications

Given that synchronization is not a concern in non-threaded applications, HashMap emerges as the preferred choice. Its unsynchronized nature allows it to outperform synchronized Hashtable, enhancing performance.

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