Difference between HashMap and LinkedHashMap

The HashMap and LinkedHashMap are the most widely used collection in java. Both are very popular to store the object based on key-value pairs. But both have some similarities and differences also. Here we will discuss the difference between HashMap and LinkedHashMap. So let’s find the HashMap vs LinkedHashMap.

HashMap vs LinkedHashMap

Difference between HashMap and LinkedHashMap

1. The most important difference between LinkedHashMap and HashMap is order. The HashMap doesn’t maintain any order of objects. But the LinkedHashMap maintains the insertion order of Object. We can change the order of the element by use of the special constructor of LinkedHashMap class.

2. The HashMap internally uses the HashTable to store the data and to perform operations on data. But LinkedHashMap uses HashTable and LinkedList to maintain the data.

3. The HashMap consumes less memory than the LinkedHashMap because the LinkedHashMap maintains the also requires more memory than HashMap because of this ordering feature. It maintains the links by use of doubly LinkedList.

4. The HashMap implements the Map interface and extends AbstractMap, but LinkedHashMap extends HashMap and implements the Map interface.

5. HashMap class was introduced in JDK 1.2 and HashMap class introduced in JDK 1.5.

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