What is the difference between HashMap and LinkedHashMap?

The main difference between HashMap and Linked HashMap is the order. HashMap is more random and lacking sensible order, while LinkedHashMap is in key insertion order, which is the order that the keys are inserted in the map.

HashMap is one of the most traditional and includes the four general-purpose implementations of the Map interface in Java based on the hashing algorithm. HashMap offers constant time performances for put and get. The class is not thread-safe but allows one null key and multiple null values. It does not maintain a particular order; it involves less memory. LinkedHashMap is part of the HashMap class, so its features are the same.