In Java, What Distinguishes A HashMap From A Hashtable?

The main differences between HashMap and Hashtable in Java are:

  1. Thread-safety: Hashtable is synchronized i.e., it is safe to be used in a multi-threaded environment. In contrast, HashMap is not thread-safe, so if multiple threads access a HashMap concurrently, it must be synchronized externally.

  2. Null values: Hashtable does not allow null keys or values. Any attempt to insert null keys or values will throw a NullPointerException. On the other hand, HashMap allows one null key and multiple null values, as it implements the Map interface.

  3. Iteration order: HashMap provides no guarantees regarding the order of its elements during iteration. The iteration order may change over time, as it is not based on the insertion order. Hashtable, on the other hand, maintains the insertion order during iteration.

  4. Performance: HashMap is generally considered faster in performance compared to Hashtable, as it is not synchronized.

  5. Legacy class: Hashtable is part of the original Java collections framework, while HashMap was introduced in Java 1.2. Therefore, Hashtable is considered a legacy class and it is recommended to use HashMap instead.

About the Author Rex

I'm a passionate tech blogger with an insatiable love for programming! From my early days tinkering with code, I've delved into web dev, mobile apps, and AI. Sharing insights and tutorials with the world is my joy, connecting me to a global community of like-minded tech enthusiasts. Python holds a special place in my heart, but I embrace all challenges. Constantly learning, I attend tech conferences, contribute to open-source projects, and engage in code review sessions. My ultimate goal is to inspire the next generation of developers and contribute positively to the ever-evolving tech landscape. Let's code together!