Java is among most robust and flexible programming languages around the globe. Its strengths lie in the strong Collections Framework, which simplifies the storage and manipulation of data. The most commonly used categories is HashMap and Hashtable both of which store data using key value pairs. Java Course in PuneAlthough they appear like they do, there are significant differences between themparticularly when it comes to synchronization, performance and handling of nulls. Knowing these distinctions will not only help in writing efficient Java code, but also improves your performance during Java interviews as well as real-world projects.In SevenMentor's Java training in Pune students get practical experience with these essential Java concepts, and are able to prepare for the top positions in the industry as well as advanced certificates.What is a HashMap?The HashMap is a new class within the Java Collections Framework, introduced in Java 1.2. It stores data in key-value pairs, where every key has a unique value and is assigned to only one value. HashMap can handle the use of a null key as well as multiple null values, which gives developers the flexibility to work with diverse data sets.Inside, HashMap uses hashing -an algorithm that computes the keys hash code to determine which data is saved inside the memory (known by the term "bucket"). If several keys produce identical hash codes (a collision), HashMap uses a linked list or a balanced tree to handle these collisions effectively.HashMap isn't synchronized. which means that multiple threads are able to modify it in parallel. This makes it more efficient but it's not safe for threads. Developers can make a HashMap synchronized using Collections.synchronizedMap() or opt for ConcurrentHashMap, which is thread-safe and designed for concurrent operations.What is a Hashtable?Hashtable is among the earliest classes of Java which was first it was introduced in Java 1.0 in the early days before it was even known that the Collections Framework existed. Similar to HashMap it also stores data using key-value pairs and utilizes hashing to retrieve data quickly. The main differentiator is Hashtable is synchronized, which means every method it uses is secure for threads by default.Due to this synchronization, only one thread is able use the Hashtable at the same time, making it more slow than HashMap for single-threaded applications. Additionally, Hashtable does not allow null keys or values, which could restrict flexibility in certain situations.While Hashtable was a key component of Java's original design, it's currently thought of as a class that's been around for a while, current applications preferring HashMap or ConcurrentHashMap to provide better efficiency and reliability.Key Differences Between HashMap and HashtableHere are the key distinctions that distinguish HashMap and Hashtable from each other:
- Synchronization HashMap cannot be synchronized (not thread-safe) but Hashtable is synced (thread-safe).
- The performance: HashMap is faster due to the lack of the overhead of synchronization. Hashtable is slower as it blocks the whole table.
- Null Handling HashMap permits one null key, as well as several null values. Hashtable does not allow null in any way.
- The Iterator type: HashMap uses an Iterator that is extremely fast and reliable. Hashtable utilizes an Enumerator however, which is not fast enough to fail.
- Its Legacy Status HashMap belongs to the Java Collections Framework; Hashtable is a class that was created in the past.
- The most preferred use is HashMap for applications that use a single thread, as well as ConcurrentHashMap for multi-threaded applications.
Internal Working MechanismEach HashMap and Hashtable make use of hashing to save and retrieve information effectively. If a key-value pair has been added to is the method of hashcoding() procedure determines the bucket's index in which the entry will be stored.If several entries are placed within one bucket (a collision) and are then linked together as chains. In Java 8, HashMap optimizes this by using Red-Black trees to handle buckets with a lot of collisions, enhancing performance up to O(log (log) in the worst-case. Hashtable, which is older, still makes use of linked lists which slows access in the event of heavy collisions.Thread Safety and Modern AlternativesIts synchronization makes sure that it's secure for multithreaded operation, however it also creates performance bottlenecks. Every write or read operation blocks the entire object which can cause a decrease in efficiency when multiple threads use the map.HashMap since it is not synchronized is more efficient and suitable for single-threaded applications. To allow parallel access Java programmers prefer ConcurrentHashMap which is locked to only specific segments rather than the entire map. This creates ConcurrentHashMap extremely thread-safe and efficient for parallel tasks.Which One Should You Use?In current Java creation, HashMap has been favored in most cases because of its rapidity and flexibility as well as integration with Collections Framework. If you require thread security then it is recommended to utilize ConcurrentHashMap in place of Hashtable because it offers greater scalability and concurrency.Hashtable is used nowadays mainly to maintain older, outdated codebases. For new applications, ConcurrentHashMap as well as HashMap are the best data structures. ConcurrentHashMap are the preferred data structures. Java Classes in PuneConclusionTo summarize To summarize, the two HashMap as well as Hashtable are incredibly efficient data structures used to store key-values However, they can be adapted to different needs in programming. HashMap is a fast versatile, flexible and widely used in contemporary Java applications, whereas Hashtable is synchronized, but it's outdated. Developers must choose the best choice based on the project's performance and concurrency requirements.If you're studying Java or preparing for an interview understanding the distinction between the two is crucial. It's not just a way to strengthen your basic Java foundation, but it will also help you gain an edge in the real-world application of software development.Learn Java the right Way by using SevenMentor PuneIn SevenMentor's Java Training in Pune, you don't only learn syntax; you learn the real-world application of programming. Our highly trained trainers assist you to learn advanced concepts such as Collections Framework, Multithreading, OOPs, Streams and exceptional Handling through practical exercises and exam preparation.No matter if you're a beginner looking to begin your coding journey, or an experienced professional looking to improve your knowledge in Java, Our Java training classes at Pune will turn you into a professional Java developer.Sign up today and become certified Java professional through SevenMentor!
