Java.util.LinkedHashMap Class
Java LinkedHashMap Class
Java.util package provides a LinkedHashMap class which is a Hash table and linked list implementation of the Map interface, with predictable iteration order. This implementation differs from HashMap in that it maintains a doubly-linked list running through all of its entries. 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
The declaration of java.util.LinkedHashMap class is:
public class LinkedHashMap<K,V>
extends HashMap<K,V>
implements Map<K,V>
Here, K and V are the type of key and value respectively maintained by the container.
Class Constructors
| S.N | Constructors & Description |
|---|---|
| 1. |
LinkedHashMap() Constructs an empty insertion-ordered LinkedHashMap instance with the default initial capacity (16) and load factor (0.75). |
| 2. |
LinkedHashMap(int initialCapacity) Constructs an empty insertion-ordered LinkedHashMap instance with the specified initial capacity and a default load factor (0.75). |
| 3. |
LinkedHashMap(int initialCapacity, float loadFactor) Constructs an empty insertion-ordered LinkedHashMap instance with the specified initial capacity and load factor. |
| 4. |
LinkedHashMap(int initialCapacity, float loadFactor, boolean accessOrder) Constructs an empty LinkedHashMap instance with the specified initial capacity, load factor and ordering mode. |
| 5. |
LinkedHashMap(Map<? extends K,? extends V> m) Constructs an insertion-ordered LinkedHashMap instance with the same mappings as the specified map. |
java.util.LinkedHashMap Methods
The java.util.LinkedHashMap class has a number of methods which are listed below:
Member Methods
| S.N | Methods & Description |
|---|---|
| 1. |
void clear() Removes all of the mappings from this map. |
| 2. |
boolean containsValue(Object value) Returns true if this map maps one or more keys to the specified value. |
| 3. |
Set<Map.Entry<K,V>> entrySet() Returns a Set view of the mappings contained in this map. |
| 4. |
void forEach(BiConsumer<? super K,? super V> action) Performs the given action for each entry in this map until all entries have been processed or the action throws an exception. |
| 5. |
V get(Object key) Returns the value to which the specified key is mapped, or null if this map contains no mapping for the key. |
| 6. |
V getOrDefault(Object key, V defaultValue) Returns the value to which the specified key is mapped, or defaultValue if this map contains no mapping for the key. |
| 7. |
Set<K> keySet() Returns a Set view of the keys contained in this map. |
| 8. |
protected boolean removeEldestEntry(Map.Entry<K,V> eldest) Returns true if this map should remove its eldest entry. |
| 9. |
void replaceAll(BiFunction<? super K,? super V,? extends V> function) 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. |
| 10. |
Collection<V> values() Returns a Collection view of the values contained in this map. |
Methods inherited
This class inherits the methods of following class:
- java.lang.Object
- java.util.AbstractMap<K,V>
- java.util.HashMap<K,V>
