OrderedFastHashMap (HtmlUnit 4.17.0 API)

java.lang.Object
- org.htmlunit.util.OrderedFastHashMap<K,V>

Type Parameters:

K - the type of the key

V - the type of the value

All Implemented Interfaces:

Serializable, Map<K,V>
```
public class OrderedFastHashMap<K,V>
extends Object
implements Map<K,V>, Serializable
```
Simple and efficient linked map or better ordered map implementation to replace the default linked list which is heavy.
This map does not support null and it is not thread-safe. It implements the map interface but only for compatibility reason in the sense of replacing a regular map. Iterator and streaming methods are either not implemented or less efficient.
It goes the extra mile to avoid the overhead of wrapper objects.
Because you typically know what you do, we run minimal index checks only and rely on the default exceptions by Java. Why should we do things twice?
Important Note: This is meant for small maps because to save on memory allocation and churn, we are not keeping a wrapper for a reference from the map to the list, only from the list to the map. Hence when you remove a key, we have to iterate the entire list. Mostly, half of it most likely, but still expensive enough. When you have something small like 10 to 20 entries, this won't matter that much especially when a remove might be a rare event.
This is based on FashHashMap from XLT which is based on a version from: https://github.com/mikvor/hashmapTest/blob/master/src/main/java/map/objobj/ObjObjMap.java No concrete license specified at the source. The project is public domain.

Author:

René Schwietzke

See Also:

Serialized Form

Constructor Summary

Constructors
Constructor and Description
`OrderedFastHashMap()` Default constructor which create an ordered map with default size.
`OrderedFastHashMap(int size)` Custom constructor to get a map with a custom size and fill factor.

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`V`	`add(K key, V value)` Append at the end.
`V`	`addFirst(K key, V value)` Insert at the beginning.
`V`	`addLast(K key, V value)` Append at the end.
`void`	`clear()` Clears the map, reuses the data structure by clearing it out.
`boolean`	`containsKey(Object key)` Checks of a key is in the map.
`boolean`	`containsValue(Object value)`
`Set<Map.Entry<K,V>>`	`entrySet()`
`V`	`get(Object key)` Get a value for a key, any key type is permitted due to the nature of the Map interface.
`org.htmlunit.util.OrderedFastHashMap.Entry<K,V>`	`getEntry(int index)` Returns an entry consisting of key and value at a given position.
`V`	`getFirst()`
`K`	`getKey(int index)` Returns the key at a certain position of the ordered list that keeps the addition order of this map.
`V`	`getLast()`
`V`	`getValue(int index)` Returns the value at a certain position of the ordered list that keeps the addition order of this map.
`boolean`	`isEmpty()`
`List<K>`	`keys()` Returns a list of all keys in order of addition.
`Set<K>`	`keySet()`
`V`	`put(K key, V value)`
`void`	`putAll(Map<? extends K,? extends V> src)`
`V`	`remove(int index)` Removes a key and value from this map based on the position in the backing list, rather by key as usual.
`V`	`remove(Object key)` Remove a key from the map.
`V`	`removeFirst()` Removes the first entry.
`V`	`removeLast()` Removes the last entry.
`void`	`reverse()` Just reverses the ordering of the map as created so far.
`int`	`size()` Returns the size of the map, effectively the number of entries.
`String`	`toString()`
`List<V>`	`values()` Returns a list of all values ordered by when the key was added.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Methods inherited from interface java.util.Map
compute, computeIfAbsent, computeIfPresent, equals, forEach, getOrDefault, hashCode, merge, putIfAbsent, remove, replace, replace, replaceAll

- Constructor Detail
  - OrderedFastHashMap
```
public OrderedFastHashMap()
```
    Default constructor which create an ordered map with default size.
  - OrderedFastHashMap
```
public OrderedFastHashMap(int size)
```
    Custom constructor to get a map with a custom size and fill factor. We are not spending time on range checks, rather use a default if things are wrong.
    
    Parameters:
    
    size - the size to use, must 0 or positive, negative values default to 0
- Method Detail
  - get
```
public V get(Object key)
```
    Get a value for a key, any key type is permitted due to the nature of the Map interface.
    
    Specified by:
    
    get in interface Map<K,V>
    
    Parameters:
    
    key - the key
    
    Returns:
    
    the value or null, if the key does not exist
  - remove
```
public V remove(Object key)
```
    Remove a key from the map. Returns the stored value or null of the key is not known.
    
    Specified by:
    
    remove in interface Map<K,V>
    
    Parameters:
    
    key - the key to remove
    
    Returns:
    
    the stored value or null if the key does not exist
  - size
```
public int size()
```
    Returns the size of the map, effectively the number of entries.
    
    Specified by:
    
    size in interface Map<K,V>
    
    Returns:
    
    the size of the map
  - keys
```
public List<K> keys()
```
    Returns a list of all keys in order of addition. This is an expensive operation, because we get a static list back that is not backed by the implementation. Changes to the returned list are not reflected in the map.
    
    Returns:
    
    a list of keys as inserted into the map
  - values
```
public List<V> values()
```
    Returns a list of all values ordered by when the key was added. This is an expensive operation, because we get a static list back that is not backed by the implementation. Changes to the returned list are not reflected in the map.
    
    Specified by:
    
    values in interface Map<K,V>
    
    Returns:
    
    a list of values
  - clear
```
public void clear()
```
    Clears the map, reuses the data structure by clearing it out. It won't shrink the underlying arrays!
    
    Specified by:
    
    clear in interface Map<K,V>
  - getEntry
```
public org.htmlunit.util.OrderedFastHashMap.Entry<K,V> getEntry(int index)
```
    Returns an entry consisting of key and value at a given position. This position relates to the ordered key list that maintain the addition order for this map.
    
    Parameters:
    
    index - the position to fetch
    
    Returns:
    
    an entry of key and value
    
    Throws:
    
    IndexOutOfBoundsException - when the ask for the position is invalid
  - getKey
```
public K getKey(int index)
```
    Returns the key at a certain position of the ordered list that keeps the addition order of this map.
    
    Parameters:
    
    index - the position to fetch
    
    Returns:
    
    the key at this position
    
    Throws:
    
    IndexOutOfBoundsException - when the ask for the position is invalid
  - getValue
```
public V getValue(int index)
```
    Returns the value at a certain position of the ordered list that keeps the addition order of this map.
    
    Parameters:
    
    index - the position to fetch
    
    Returns:
    
    the value at this position
    
    Throws:
    
    IndexOutOfBoundsException - when the ask for the position is invalid
  - remove
```
public V remove(int index)
```
    Removes a key and value from this map based on the position in the backing list, rather by key as usual.
    
    Parameters:
    
    index - the position to remove the data from
    
    Returns:
    
    the value stored
    
    Throws:
    
    IndexOutOfBoundsException - when the ask for the position is invalid
  - put
```
public V put(K key,
             V value)
```
    Specified by:
    
    put in interface Map<K,V>
  - addFirst
```
public V addFirst(K key,
                  V value)
```
    Insert at the beginning.
    
    Parameters:
    
    key - the key
    
    value - the value
    
    Returns:
    
    the inserted value
  - add
```
public V add(K key,
             V value)
```
    Append at the end.
    
    Parameters:
    
    key - the key
    
    value - the value
    
    Returns:
    
    the appended value
  - addLast
```
public V addLast(K key,
                 V value)
```
    Append at the end.
    
    Parameters:
    
    key - the key
    
    value - the value
    
    Returns:
    
    the appended value
  - getFirst
```
public V getFirst()
```
    Returns:
    
    the first value.
  - getLast
```
public V getLast()
```
    Returns:
    
    the last value.
  - removeFirst
```
public V removeFirst()
```
    Removes the first entry.
    
    Returns:
    
    the removed value or null if the map was empty.
  - removeLast
```
public V removeLast()
```
    Removes the last entry.
    
    Returns:
    
    the removed value or null if the map was empty.
  - containsKey
```
public boolean containsKey(Object key)
```
    Checks of a key is in the map.
    
    Specified by:
    
    containsKey in interface Map<K,V>
    
    Parameters:
    
    key - the key to check
    
    Returns:
    
    true of the key is in the map, false otherwise
  - containsValue
```
public boolean containsValue(Object value)
```
    Specified by:
    
    containsValue in interface Map<K,V>
  - isEmpty
```
public boolean isEmpty()
```
    Specified by:
    
    isEmpty in interface Map<K,V>
  - entrySet
```
public Set<Map.Entry<K,V>> entrySet()
```
    Specified by:
    
    entrySet in interface Map<K,V>
  - keySet
```
public Set<K> keySet()
```
    Specified by:
    
    keySet in interface Map<K,V>
  - reverse
```
public void reverse()
```
    Just reverses the ordering of the map as created so far.
  - putAll
```
public void putAll(Map<? extends K,? extends V> src)
```
    Specified by:
    
    putAll in interface Map<K,V>
  - toString
```
public String toString()
```
    Overrides:
    
    toString in class Object

Class OrderedFastHashMap<K,V>

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Methods inherited from interface java.util.Map

Constructor Detail

OrderedFastHashMap

OrderedFastHashMap

Method Detail

get

remove

size

keys

values

clear

getEntry

getKey

getValue

remove

put

addFirst

add

addLast

getFirst

getLast

removeFirst

removeLast

containsKey

containsValue

isEmpty

entrySet

keySet

reverse

putAll

toString