@Beta public class IntHashMap<V> extends AbstractIntMap<V> implements Serializable
This implementation provides constant-time performance for the basic operations (get and put), assuming the hash function disperses the elements properly among the buckets. Iteration over collection views requires time proportional to the "capacity" of the IntHashMap instance (the number of buckets) plus its size (the number of key-value mappings). Thus, it's very important not to set the intial capacity too high (or the load factor too low) if iteration performance is important.
An instance of HashMap has two parameters that affect its performance: initial capacity and load factor. The capacity is the number of buckets in the hash table, and the initial capacity is simply the capacity at the time the hash table is created. The load factor is a measure of how full the hash table is allowed to get before its capacity is automatically increased. When the number of entries in the hash table exceeds the product of the load factor and the current capacity, the capacity is roughly doubled by calling the rehash method.
As a general rule, the default load factor (.75) offers a good tradeoff between time and space costs. Higher values decrease the space overhead but increase the lookup cost (reflected in most of the operations of the IntHashMap class, including get and put). The expected number of entries in the map and its load factor should be taken into account when setting its initial capacity, so as to minimize the number of rehash operations. If the initial capacity is greater than the maximum number of entries divided by the load factor, no rehash operations will ever occur.
If many mappings are to be stored in a IntHashMap instance, creating it with a sufficiently large capacity will allow the mappings to be stored more efficiently than letting it perform automatic rehashing as needed to grow the table.
Note that this implementation is not synchronized. If multiple threads access this map concurrently, and at least one of the threads modifies the map structurally, it must be synchronized externally. (A structural modification is any operation that adds or deletes one or more mappings; merely changing the value associated with a key that an instance already contains is not a structural modification.) This is typically accomplished by synchronizing on some object that naturally encapsulates the map. The iterators returned by all of this class's "collection view methods" are fail-fast: if the map is structurally modified at any time after the iterator is created, in any way except through the iterator's own remove or add methods, the iterator will throw a ConcurrentModificationException. Thus, in the face of concurrent modification, the iterator fails quickly and cleanly, rather than risking arbitrary, non-deterministic behavior at an undetermined time in the future. Beta class. Classes under com.force.i18n.commons package will be moved into a dedicated project.
IntMap,
HashMap,
Serialized FormAbstractIntMap.SimpleEntry<V>IntMap.Entry<V>| Constructor and Description |
|---|
IntHashMap()
Constructs a new, empty map with a default capacity, 101, and load
factor, which is 0.75.
|
IntHashMap(int initialCapacity)
Constructs a new, empty map with the specified initial capacity
and default load factor, which is 0.75.
|
IntHashMap(int initialCapacity,
float loadFactor)
Constructs a new, empty map with the specified initial
capacity and the specified load factor.
|
IntHashMap(IntMap<? extends V> t)
Constructs a new map with the same mappings as the given map.
|
| Modifier and Type | Method and Description |
|---|---|
int |
capacity() |
void |
clear()
Removes all mappings from this map.
|
boolean |
containsKey(int key)
Returns true if this map contains a mapping for the specified
key.
|
boolean |
containsValue(Object value)
Returns true if this map maps one or more keys to the
specified value.
|
Set<IntMap.Entry<V>> |
entrySet()
Returns a collection view of the mappings contained in this map.
|
V |
get(int key)
Returns the value to which this map maps the specified key.
|
IntSet |
keySet()
Returns a set view of the keys contained in this map.
|
V |
put(int key,
V value)
Associates the specified value with the specified key in this map.
|
V |
remove(int key)
Removes the mapping for this key from this map if present.
|
int |
size()
Returns the number of key-value mappings in this map.
|
Collection<V> |
values()
Returns a collection view of the values contained in this map.
|
public IntHashMap(int initialCapacity,
float loadFactor)
initialCapacity - the initial capacity of the HashMap.loadFactor - the load factor of the HashMapIllegalArgumentException - if the initial capacity is less
than zero, or if the load factor is nonpositive.public IntHashMap(int initialCapacity)
initialCapacity - the initial capacity of the HashMap.IllegalArgumentException - if the initial capacity is less
than zero.public IntHashMap()
public IntHashMap(IntMap<? extends V> t)
t - the map whose mappings are to be placed in this map.public int size()
public boolean containsValue(Object value)
containsValue in interface IntMap<V>value - value whose presence in this map is to be tested.public boolean containsKey(int key)
containsKey in interface IntMap<V>key - key whose presence in this Map is to be tested.public V get(int key)
public V put(int key, V value)
put in interface IntMap<V>key - key with which the specified value is to be associated.value - value to be associated with the specified key.public V remove(int key)
remove in interface IntMap<V>key - key whose mapping is to be removed from the map.public void clear()
public IntSet keySet()
public Collection<V> values()
public Set<IntMap.Entry<V>> entrySet()
entrySet in interface IntMap<V>IntMap.Entrypublic int capacity()
Copyright (c) 2016-2017, Salesforce.com, Inc. All rights reserved. Licensed under the BSD 3-Clause license. For full license text, see the LICENSE.txt file in the repository.