#Linked hashmap how to#
#Linked hashmap code#

In this class, the data is stored in the form of nodes. Therefore, the class is declared as: public class LinkedHashMap extends HashMap implements Map.

#Linked hashmap code#

* This code is distributed under Apache License 2.0. A LinkedHashMap is an extension of the HashMap class and it implements the Map interface. Here is the implementation of LRU Cache using LinkedHashMap in Java. In Java, get () method of LinkedHashMap class is used to retrieve or fetch the value mapped by a particular key mentioned in the parameter. In our implementation, we will return true when size becomes greater than the capacity to let LinkedHashMap remove the least recently accessed element. However in this case, we will be configuring LinkedHashMap to maintain the data in Access order by setting the accessOrder flag to true in its three argument copy constructor.Īdditionally, we will override method removeEldestEntry that LinkedHashMap calls after every put method call to check whether it should remove the eldest element. After that, we sort the list based on the values. The simplest way to sort a LinkedHashMap by values is to convert it into a list of key-value pairs. Its initial default capacity is 16 with a load factor of 0.75. A LinkedHashMap can have only one null key and multiple null values. LinkedHashMap can be used to maintain insertion order, on which keys are inserted into Map or it can also be used to maintain an access order, on which keys are. It maintains insertion order for its elements. It contains the elements in key-value pair form.

#Linked hashmap how to#

We’ll demonstrate several approaches how to achieve it. LinkedHashMap extends the HashMap class and implements the Map interface. By default, LinkedHashMap maintains the data in Insertion order. In this tutorial, we’ll show how to sort a LinkedHashMap based on its values. Unlike HashMap, LinkedHashMap is based on HashTable and Linked list. Java LinkedHashMap class is Hashtable and Linked list implementation of the Map interface, with predictable iteration order. LinkedHashMap can order the elements in Insertion order as well as Access order. A LinkedHashMap like HashMap is a simple yet powerful way to store and get data.

We will be extending LinkedHashMap class provided by Java to implement our LRUCache. LinkedHashMap is a Hash table and linked list implementation of the Map interface, with predictable iteration order.