How to Update the Value of an Existing Key in a LinkedHashMap in Java?

Last Updated : 09 Feb, 2024

In Java programming, a LinkedHahMap is like HashMap with additional features in the Java Collections framework. It keeps track of the order in which elements were added. A regular HashMap doesn't have a fixed order for elements. LinkedHashMap uses an approach with a doubly-linked list to remember the order of inserted keys.

Key terminologies:

Key-value pair: In a LinkedHashMap, all the data can be stored in the form of a key-value pair, where the key is a unique value for each element in the map and the value is assigned to a particular key.
KeySet: The KeySet in a LinkedHashMap is gathered using the method and returns a set of all keys in the map.
Insertion Order: The elements inserted into the LinkedHashMap are maintained in the order.
Double-LinkedList: LinkedHashMap uses the doubly-linked list to maintain the order of the elements.

Implementation to Update the Existing Keys

In Java, the implementation of the update of the values of an existing key in a LinkedHashMap using the put() method. It can be used to update the values of the existing key in the LinkedHashMap.

put(): This method can be used to add new key values to the map and also update the values if the key already exists.

Example:

Input: Original LinkedHashMap: {Key1=1, Key2=2, Key3=3}

Output: Value updated for key 'Key2'
Updated LinkedHashMap: {Key1=1, Key2=22, Key3=3}

Java Program to Update the Value of an Existing Key in a LinkedHashMap

Below is the implementation of Updating the Value of an Existing Key in a LinkedHashMap:

Java

// Java Program to update the value of an existing key in a LinkedHashMap import java.util.LinkedHashMap; public class GFGUpdateLinkedHashMap  {     public static void main(String[] args)      {         // Create a sample LinkedHashMap named as linkedHashMap         LinkedHashMap<String, Integer> linkedHashMap = new LinkedHashMap<>();          // Add some key-value pairs         linkedHashMap.put("Key1", 1);         linkedHashMap.put("Key2", 2);         linkedHashMap.put("Key3", 3);          // print the original map         System.out.println("Original LinkedHashMap: " + linkedHashMap);          // Update the existing value with the key "Two"         updateValue(linkedHashMap, "Key2", 22);          // print the updated map         System.out.println("Updated LinkedHashMap: " + linkedHashMap);     }      // Method to update the existing key value in a LinkedHashMap     private static <K, V> void updateValue(LinkedHashMap<K, V> map, K key, V newValue)      {         if (map.containsKey(key))          {             map.put(key, newValue);             System.out.println("Value updated for key '" + key + "'");         } else          {             System.out.println("Key '" + key + "' not found in the LinkedHashMap");         }     } }

Output

Original LinkedHashMap: {Key1=1, Key2=2, Key3=3}  Value updated for key 'Key2'  Updated LinkedHashMap: {Key1=1, Key2=22, Key3=3}

Explanation of the Program:

This Java program demonstrates updating the value of an existing key in a LinkedHashMap.
It starts by creating a LinkedHashMap named "linkedHashMap" with some key-value pairs.
After printing the original map, it uses a method called "updateValue" to update the value associated with the key "Key2" to 22.
Finally, it prints the updated map. In simple terms, it's like having a list of things with names and changing the value associated with one of those names while keeping the rest unchanged.

How to Check if LinkedHashMap Contains a value in Java?

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How to Update the Value of an Existing Key in a LinkedHashMap in Java?

Implementation to Update the Existing Keys

Example:

Java Program to Update the Value of an Existing Key in a LinkedHashMap

Explanation of the Program:

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