How to Add Key-Value pairs to LinkedHashMap in Java?

Last Updated : 22 Dec, 2020

LinkedHashMap is a Hash table and linked list implementation of the Map interface. In LinkedHashMap order of key-value pair depends on the order in which keys were inserted into the map. Insertion order does not affect if a key is reinserted into the map.

Example:

Input:        Key: 1       Value : 1221       Key: 2       Value : 2112  Output:      Keys : [1,2]      Values : [1221,2112]      Key-Value pairs : [1=1221, 2=2112]

Methods Use:

put(Key, Value): First parameter as key and second parameter as Value.
keySet(): Creates a set out of the key elements contained in the hash map.
values(): Create a set out of the values in the hash map.

Approach:

Create two-variable named as Key and Value
Accept the input from user in Key and in Value
Use put() method to add Key-Value pair inside the LinkedHashMap

Below is the implementation of the above approach:

Java

   // Java Program to add key-value  
// pairs to LinkedHashMap 
import java.util.*; 
public class Main { 
    
    public static void main(String[] args) 
    { 
        // create an instance of LinkedHashMap 
        LinkedHashMap<Integer, Integer> map 
            = new LinkedHashMap<Integer, Integer>(); 
  
        int num, key, val; 
        num = 2; 
        for (int i = 0; i < num; i++) { 
            
            // Taking inputs from user 
            key = i + 1; 
            val = key * 10; 
  
            // Add mappings using put method 
            map.put(key, val); 
        } 
        // Displaying key 
        System.out.println("Keys: " + map.keySet()); 
  
        // Displaying value 
        System.out.println("Values: " + map.values()); 
  
        // Displaying key-value pair 
        System.out.println("Key-Value pairs: "
                           + map.entrySet()); 
    } 
}
 
  

Output

Keys: [1, 2]  Values: [10, 20]  Key-Value pairs: [1=10, 2=20]

Time Complexity: O(1)

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