Java LinkedHashMap
Last Updated : 28 Mar 2026
Java LinkedHashMap is used to store data in key-value pairs while maintaining the insertion order. It is useful when you need both fast access and ordered data. It is a part of the Java Collection Framework.
In this chapter, you will learn about the Java LinkedHashMap class, its features, and examples.
What is LinkedHashMap in Java?
Java LinkedHashMap class is a Hashtable and Linked List implementation of the Map interface. It extends the HashMap class and implements the Map interface.
It stores data as key-value pairs and maintains the order in which elements are inserted.
Features of LinkedHashMap
Here are some of the key features of LinkedHashMap:
- Java LinkedHashMap stores values based on keys.
- It contains unique keys.
- It allows one null key and multiple null values.
- It is non-synchronized.
- It maintains insertion order.
- The default capacity is 16 with a load factor of 0.75.
LinkedHashMap class declaration
Let's see the declaration for java.util.LinkedHashMap class.
LinkedHashMap class Parameters
Let's see the parameters for java.util.LinkedHashMap class:
- K: It is the type of keys maintained by this map.
- V: It is the type of mapped values.
Constructors of LinkedHashMap Class
Java LinkedHashMap class provides different constructors to create and initialize a LinkedHashMap.
1. LinkedHashMap()
It is used to construct a default LinkedHashMap.
Here is the syntax:
2. LinkedHashMap(int capacity)
It is used to construct a LinkedHashMap with the specified initial capacity.
Here is the syntax:
3. LinkedHashMap(int capacity, float loadFactor)
It is used to construct a LinkedHashMap with the specified capacity and load factor.
Here is the syntax:
4. LinkedHashMap(int capacity, float loadFactor, boolean accessOrder)
It is used to construct a LinkedHashMap with the specified capacity, load factor, and ordering mode (insertion order or access order).
Here is the syntax:
5. LinkedHashMap(Map m)
It is used to construct a LinkedHashMap containing the elements of the specified Map.
Here is the syntax:
Methods of LinkedHashMap class
The following table shows the commonly used methods of the LinkedHashMap class:
| Method | Description |
|---|---|
| V get(Object key) | It returns the value to which the specified key is mapped. |
| void clear() | It removes all the key-value pairs from a map. |
| boolean containsValue(Object value) | It returns true if the map maps one or more keys to the specified value. |
| Set<Map.Entry<K,V>> entrySet() | It returns a Set view of the mappings contained in the map. |
| void forEach(BiConsumer<? super K,? super V> action) | It performs the given action for each entry in the map until all entries have been processed or the action throws an exception. |
| V getOrDefault(Object key, V defaultValue) | It returns the value to which the specified key is mapped or defaultValue if this map contains no mapping for the key. |
| Set<K> keySet() | It returns a Set view of the keys contained in the map |
| protected boolean removeEldestEntry(Map.Entry<K,V> eldest) | It returns true on removing its eldest entry. |
| void replaceAll(BiFunction<? super K,? super V,? extends V> function) | It replaces each entry's value with the result of invoking the given function on that entry until all entries have been processed or the function throws an exception. |
| Collection<V> values() | It returns a Collection view of the values contained in this map. |
Examples of LinkedHashMap
Here are some examples of the Java LinkedHashMap class to understand its usage.
Example 1: Simple LinkedHashMap Example
In this example, we are creating a LinkedHashMap, adding elements, and traversing it.
Output:
100 Amit 101 Vijay 102 Rahul
Example 2: Accessing Keys and Values
In this example, we are fetching keys, values, and key-value pairs from LinkedHashMap.
Output:
Keys: [100, 101, 102] Values: [Amit, Vijay, Rahul] Key-Value pairs: [100=Amit, 101=Vijay, 102=Rahul]
Example 3: Removing Elements from LinkedHashMap
In this example, we are removing elements using the remove() method.
Output:
Before invoking remove() method: {101=Amit, 102=Vijay, 103=Rahul}
After invoking remove() method: {101=Amit, 103=Rahul}
Example 4: Storing Objects in LinkedHashMap
In this example, we are storing user-defined Book objects in a LinkedHashMap.
Output:
2 Details: 102 Data Communications & Networking Forouzan Mc Graw Hill 4 1 Details: 101 Let us C Yashwant Kanetkar BPB 8 3 Details: 103 Operating System Galvin Wiley 6