Ever wondered what’s the difference between a Linkedhashmap and a Hashmap in Java? Do they perform equal functions? What are the advantages and disadvantages of using one over the other? This article looks at the two data structures, and explains the differences, advantages and disadvantages in detail, helping you decide when it is best to use each.

Key Differences Between Linkedhashmap and Hashmap

The main difference between a Linkedhashmap and a Hashmap is the ordering of elements. A Linkedhashmap stores its elements in the order they are placed or accessed, while a Hashmap does not. This means that if you traverse the Linkedhashmap in order of insertion, each element is returned in the same order it was placed in. However, a Hashmap does not have an ordering system – if the elements are traversed in the same order, there is no guarantee that they will be returned in the same order they were placed in.

Another key difference between the two data structures is that a Linkedhashmap allows you to access elements by a key, while a Hashmap does not. This means that if you have data associated with a certain key, such as names associated with numbers, then you can use a Linkedhashmap to access the information with ease. With a Hashmap, you would have to search for the entry associated with that key.

Linkedhashmaps also offer better performance than Hashmaps when it comes to retrieving elements. This is because Linkedhashmaps use a doubly-linked list to store elements, which allows for faster access times. Hashmaps, on the other hand, use an array to store elements, which can be slower when it comes to retrieving elements.

Advantages of Using Linkedhashmap

One of the major advantages of using a Linkedhashmap is that it offers fast access to elements through the use of a key. This makes it ideal for applications where fast access to data is needed. Another advantage is that it allows for efficient storage of data, with much smaller objects containing more data than in a Hashmap.

Linkedhashmaps are also very useful when dealing with large amounts of data. Because the order of elements stays consistent throughout, there is no need to store them all in memory. Instead, you can access only the data that you need at a given time and discard it once you’re done, reducing memory and making your application more efficient.

In addition, Linkedhashmaps are thread-safe, meaning that multiple threads can access the same data without any risk of data corruption. This makes them ideal for applications that require multiple threads to access the same data, such as web servers.

Disadvantages of Using Linkedhashmap

One disadvantage to using a Linkedhashmap is that it requires more overhead than a Hashmap. This includes extra memory for storing the order of elements and more time for accessing stored data. Another disadvantage is that it does not have the same level of flexibility as a Hashmap; it is not suitable for applications that require frequent changes or updates to their datasets.

Additionally, Linkedhashmaps are not thread-safe, meaning that multiple threads cannot access the same Linkedhashmap at the same time. This can lead to data corruption and other issues if not properly managed. Furthermore, Linkedhashmaps are not as efficient as Hashmaps when it comes to searching for elements, as the order of elements must be taken into account.

Advantages of Using Hashmap

The main advantage of using a Hashmap is that it offers extremely fast access times for data retrieval. This makes it ideal for applications that require constant updating or frequent changes to their datasets. Another advantage is that it does not require additional memory for storing the order of elements. This makes it more memory efficient than a Linkedhashmap in some applications.

Hashmaps also provide a high degree of flexibility when it comes to data manipulation. It allows for the addition, removal, and modification of elements without having to re-order the entire data structure. This makes it ideal for applications that require frequent changes to their datasets. Additionally, Hashmaps are not limited to a single data type, allowing for the storage of multiple data types in the same structure.

Disadvantages of Using Hashmap

The primary disadvantage of using a Hashmap is that there is no way to guarantee that accessing elements will always return them in the same order they were placed. This can lead to confusion or errors in some applications. Another disadvantage is that it does not offer access to elements by key. This means that if you need to look up data based on a specific key, then you will have to go through the whole dataset manually to find what you’re looking for.

In addition, Hashmaps are not thread-safe, meaning that multiple threads cannot access the same Hashmap at the same time. This can lead to data corruption or other errors if multiple threads are trying to access the same data. Finally, Hashmaps are not suitable for storing large amounts of data, as they can become slow and inefficient when dealing with large datasets.

Pros and Cons of Both Linkedhashmap and Hashmap

When comparing Linkedhashmaps and Hashmaps, it’s important to take into account all the pros and cons of each. Linkedhashmaps are great for applications where fast access to data and efficient storage are needed. However, they require more overhead and may not be suitable for applications that require frequent changes or updates to their datasets. On the other hand, Hashmaps offer faster access times for retrieving data and do not require extra memory to store keys. However, they do not guarantee that elements are returned in the same order as they were placed in and do not offer access to elements by key.

Linkedhashmaps also provide the ability to iterate over the elements in the order they were inserted, which can be useful for applications that need to maintain the order of elements. Hashmaps, on the other hand, do not provide this feature. Additionally, Linkedhashmaps are more memory-efficient than Hashmaps, as they do not require extra memory to store keys. This can be beneficial for applications that need to store large amounts of data.

When Should You Use Linkedhashmap or Hashmap?

It depends on what kind of application you are building. If you need data which must be returned in the same order as it was placed in, then a Linkedhashmap is a good choice. If data needs to be accessed quickly, based on its key, then a Linkedhashmap may be better. If your application requires frequent changes or updates to its dataset, then a Hashmap may offer better performance.

Common Use Cases for Each Data Structure

Linkedhashmaps are most commonly used for storing information associated with unique keys and then retrieving that data quickly. This makes them great for mapping strings to objects or numbers and then using them for quick lookups. They are also suitable for applications where it is important to have a record of the order the data was added.

Hashmaps, on the other hand, are best used for applications that require frequent updates or changes to their dataset. Because they don’t store the order of elements, they are more efficient when it comes to memory usage. They are also great for applications where elements don’t need to be accessed by key.

Conclusion

In conclusion, there’s no one-size-fits-all solution when it comes to choosing between Linkedhashmaps and Hashmaps in Java. Both data structures come with their own advantages and disadvantages, and which one you choose should depend on factors such as efficiency and speed of access as well as whether or not you need a guaranteed order of elements returned.