HashMap and Hashtable are both implementations of the Map interface in Java, but they have several key differences. Here’s a concise comparison:
Comparison Table: HashMap vs Hashtable
| Feature | HashMap | Hashtable |
|---|---|---|
| Synchronization | Not synchronized (not thread-safe) | Synchronized (thread-safe) |
| Null Keys and Values | Allows one null key and multiple null values | Does not allow null keys or values |
| Performance | Generally faster due to no synchronization overhead | Slower due to synchronization overhead |
| Iteration | Uses Iterator (fail-fast) | Uses Enumerator (not fail-fast) |
| Legacy Status | Part of the Java Collections Framework (Java 2) | A legacy class (part of Java since version 1.0) |
Conclusion
The choice between HashMap and Hashtable depends on your specific requirements regarding thread safety, performance, and the need to store null values. For most modern applications, HashMap is preferred due to its efficiency and flexibility.
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