Difference Between HashMap and LinkedHashMap in Java

In this post, we will understand the difference between HashMap and LinkedHashMap in Java.

HashMap

• In this structure, the order of insertion is not preserved.

• It uses the HashTable to store maps.

• It extends the ‘AbstractMap’.

• It implements the ‘Map’ interface.

• This was introduced in JDK 2.0.

• It has a relatively low overhead.

LinkedHashMap

• In this structure, the order of insertion is not preserved.

• It uses the HashTable and Linked List to store maps.

• It extends the ‘Hashmap’.

• It implements the ‘Map’ interface.

• This was introduced in JDK 4.0.

• It has a relatively higher overhead.

• This is because it has to maintain the order of entries in the map structure.