Java LinkedHashMap Class

Introduction

The Java LinkedHashMap class is Hash table and Linked list implementation of the Map interface, with predictable iteration order. Following are the important points about LinkedHashMap −

• The class provides all of the optional Map operations, and permits null elements.

• The Iteration over a HashMap is likely to be more expensive.

Class declaration

Following is the declaration for java.util.LinkedHashMap class −

public class LinkedHashMap<K,V>
   extends HashMap<K,V>
   implements Map<K,V>

Parameters

Following is the parameter for java.util.LinkedHashMap class −

• K − This is the type of keys maintained by this map.

• V − This is the the type of mapped values.

Class constructors

Class methods

Methods inherited

This class inherits methods from the following classes −

• java.util.HashMap
• java.util.AbstarctMap
• java.util.Object
• java.util.Map

Getting a Value from LinkedHashMap Example

The following example shows the usage of Java LinkedHashMap get() method to get a value based on a key from a Map. We've created a Map object of Integer,Integer. Then few entries are added, map is printed. Using get() method, a value is retrieved and printed.

package com.tutorialspoint;

import java.util.LinkedHashMap;

public class LinkedHashMapDemo {
   public static void main(String args[]) {
      
      // create hash map
      LinkedHashMap<Integer,Integer> newmap = new LinkedHashMap<>();

      // populate hash map
      newmap.put(1, 1);
      newmap.put(2, 2);
      newmap.put(3, 3); 

      System.out.println("Initial map elements: " + newmap);

      System.out.println("Value: " + newmap.get(1));
   }    
}

Output

Let us compile and run the above program, this will produce the following result.

Initial map elements: {1=1, 2=2, 3=3}
Value: 1