Java
Hashtable vs HashMap in Java
Compare Hashtable and HashMap by synchronization, performance, null handling, and everyday use.
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| Feature | Hashtable | HashMap |
|---|---|---|
| Introduced | Java 1.0 (Legacy class) | Java 1.2 (Collections Framework) |
| Synchronization | Thread-safe (synchronized methods) | Not thread-safe |
| Performance | Slower due to synchronization overhead | Faster due to no synchronization |
| Null Keys | Does not allow null keys | Allows one null key |
| Null Values | Does not allow null values | Allows multiple null values |
| Inheritance | Extends Dictionary class |
Extends AbstractMap class |
| Iterator | Enumerator (not fail-fast) |
Iterator (fail-fast) |
| Fail-Fast | Enumeration is not fail-fast | Iterator throws ConcurrentModificationException if modified during iteration |
| Default Capacity | 11 | 16 |
| Load Factor | 0.75 | 0.75 |
| Use Case | Suitable for thread-safe applications | Preferred for non-thread-safe applications |
| Modern Usage | Rarely used due to ConcurrentHashMap |
Widely used due to flexibility and performance |