We explain the difference between HashMap and LinkedHashMap with table. Java is a class-oriented programming language used to implement commands with the fewest dependencies. Map Interface in Java represents the relationship between a key and its value. Several groups of map implementations maintain the map interface.
HashMap and LinkedHashMap are two popularly used Java map implementations. The similarity between the two is that they are not in sync. they also have similarities in their performances. But what is the difference between the two?
HashMap is Java’s Map implementation that uses and extends the AbstractMap class to help create a collection of inheritances that belong to the same class. The items entered do not have an order and the order in which they are entered is not stored either. Difference between HashMap and LinkedHashMap
LinkedHashMap is another implementation of Map that is a subclass of HashMap. Since they have key insertion order, your applications are in areas where insertion and access order is important. They also have more memory than HashMap.
What is HashMap?
HashMap is a map implementation that you implement and extend in AbstractMap to help create a collection of inheritances that belong to the same class. It is a class that allows you to store keys and their values to form a map interface.
HashMap is out of sync. You can also store null values, but only a null key needs to be defined. It wouldn’t work with multiple null keys. This is also because the stored keys must be unique.
Even if a duplicate one is stored, it is replaced by the original in the list. The characteristic that differentiates it from the other map implementation groups is that they do not have a command to enter the key or to store the order in which it is entered.
The data structure can be easily retrieved from a HashMap. The recovered data can also be easily modified, added or deleted. So its main applications are in places that require a quick recovery process, as well as other general purposes. Difference between HashMap and LinkedHashMap
What is LinkedHashMap?
LinkedHashMap is also a map implementation group. They are a subgroup of HashMap but it extends and implements the HashMap itself that extends to AbstractMap and then to the map interface. Difference between HashMap and LinkedHashMap
LinkedHashMap is also not synced or linked. Although the entered values must be unique, they can have more than one null value in the list, but only one null key.
In this map implementation, keys are entered in order, or what is known as the key insertion order. The order of the keys entered is also preserved in the same way. Difference between HashMap and LinkedHashMap
This is ignored and maintained by doubly linked lists that run on all lists. Since they maintain order, their application in the areas where the order of insertion and access is important.
Difference between HashMap and LinkedHashMap with table
The difference between HashMap and LinkedHashMap is that HashMap does not preserve the order in which keys or elements are entered, while LinkedHashMap follows the order of key insertion and preserves the order of elements.
Comparison table between HashMap and LinkedHashMap
| Comparison parameters | HashMap | LinkedHashMap |
| Sense | It is an implementation of Java Map that uses the AbstractMap class and helps to create a collection of inheritances. | It is also a type of Java Map and is a subclass of HashMap that implements Hashtable and Linked List of Map. |
| Elements | The elements entered in a HashMap are not in order. | Items are known to be in key insertion order. |
| Order | The HashMap does not preserve the order in which the elements are entered. | Since they are in key insertion order, the input order of the elements is preserved. |
| Data structure | They are stored as a bucket list and implemented as a hash table in the map interface. | LinkedHashMap has a doubly linked list that loops through all the lists stored in it. |
| Recovery | Retrieving or performing other similar tasks on lists stored in HashMap is easy. | Retrieving, removing or adding entries in LinkedHashMap is more difficult than in HashMap. |
| Applications | It is used in locations to facilitate retrieval and for other general purposes. | It is applied or used in places where the insertion or access order matters. As LRU cache. |
Key Difference between HashMap and LinkedHashMap
- HashMap is a popular Java Map implementation that uses the AbstractMap class and you can extend it to aid in creating a collection of AbstractMap inheritances. LinkedHashMap is a subclass of HashMap and extends HashMap and implements Linked List of Map.
- The elements entered in HashMap do not have a particular order while LinkedHashMap follows the order of insertion of keys. Difference between HashMap and LinkedHashMap
- The main difference is the preservation of the order of the two maps. HashMap does not preserve the order in which keys or elements are entered. Whereas, since LinkedHashMap follows the key insertion order, they preserve the order in which the elements are entered.
- The HashMap data structure is stored as lists of buckets that have the Hashtable implemented on top of them. If there are more than a specified number of inputs, they are changed to a balanced form. On the other hand, LinkedHashMap has doubly linked lists that run through all stored lists to manage its data structure. Difference between HashMap and LinkedHashMap
- Retrieve and perform functions like delete, adding data entries is easy in HashMap. But performing the same functions in LinkedHashMap is more difficult than in HashMap.
- Since data entry retrieval is easier, HashMap is used for quick data retrieval and other general purposes. On the other hand, LinkedHashMap is used in places where the order of insertion or access is important. As in the LRU cache.
Final Thought
HashMap and LinkedHashMap are two Java map implementations that are used to maintain the map interface. Although they have some similarities, they have great differences between them that led to the need for the two groups. Difference between HashMap and LinkedHashMap
HashMap is the Map implementation that implements and extends AbstractMap. They also have a faster data recovery speed and performing functions like adding and deleting entries in this data is also faster.
LinkedHashMap is a subclass of HashMap and is also an implementation of Map that implements and extends HashMap. The elements entered are stored according to the order that was entered in the Access Order.
The difference between HashMap and LinkedHashMap is also that HashMap has higher retrieval speed, while LinkedHashMap has higher memory compared to HashMap.
