Package arc.struct

Class IntMap<V>

java.lang.Object
arc.struct.IntMap<V>
All Implemented Interfaces:
Iterable<IntMap.Entry<V>>
public class IntMap<V> extends Object implements Iterable<IntMap.Entry<V>>
An unordered map that uses int keys. This implementation is a cuckoo hash map using 3 hashes, random walking, and a small stash for problematic keys. Null values are allowed. No allocation is done except when growing the table size.

This map performs very fast get, containsKey, and remove (typically O(1), worst case O(log(n))). Put may be a bit slower, depending on hash collisions. Load factors greater than 0.91 greatly increase the chances the map will have to rehash to the next higher POT size.

  • Nested Class Summary

    Nested Classes
    Modifier and Type
    Class
    Description
    static class 
    IntMap.Entries<V>
     
    static class 
    IntMap.Entry<V>
     
    static class 
    IntMap.Keys
     
    static class 
    IntMap.Values<V>
     

  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    int
    size
     

  • Constructor Summary

    Constructors
    Constructor
    Description
    IntMap()
    Creates a new map with an initial capacity of 51 and a load factor of 0.8.
    IntMap(int initialCapacity)
    Creates a new map with a load factor of 0.8.
    IntMap(int initialCapacity, float loadFactor)
    Creates a new map with the specified initial capacity and load factor.
    IntMap(IntMap<? extends V> map)
    Creates a new map identical to the specified map.

  • Method Summary

    Modifier and Type
    Method
    Description
    void
    clear()
     
    void
    clear(int maximumCapacity)
    Clears the map and reduces the size of the backing arrays to be the specified capacity if they are larger.
    boolean
    containsKey(int key)
     
    boolean
    containsValue(Object value, boolean identity)
    Returns true if the specified value is in the map.
    void
    ensureCapacity(int additionalCapacity)
    Increases the size of the backing array to accommodate the specified number of additional items.
    IntMap.Entries<V>
    entries()
    Returns an iterator for the entries in the map.
    boolean
    equals(Object obj)
     
    int
    findKey(Object value, boolean identity, int notFound)
    Returns the key for the specified value, or notFound if it is not in the map.
    V
    get(int key)
     
    V
    get(int key, Prov<V> defaultValue)
     
    V
    get(int key, V defaultValue)
     
    int
    hashCode()
     
    boolean
    isEmpty()
    Returns true if the map is empty.
    Iterator<IntMap.Entry<V>>
    iterator()
     
    IntMap.Keys
    keys()
    Returns an iterator for the keys in the map.
    static <V> IntMap<V>
    of(Object... values)
     
    V
    put(int key, V value)
     
    void
    putAll(IntMap<? extends V> map)
     
    V
    remove(int key)
     
    void
    shrink(int maximumCapacity)
    Reduces the size of the backing arrays to be the specified capacity or less.
    String
    toString()
     
    IntMap.Values<V>
    values()
    Returns an iterator for the values in the map.

    Methods inherited from class java.lang.Object

    clone, finalize, getClass, notify, notifyAll, wait, wait, wait

    Methods inherited from interface java.lang.Iterable

    forEach, spliterator

  • Field Details

    • size

      public int size

  • Constructor Details

    • IntMap

      public IntMap()
      Creates a new map with an initial capacity of 51 and a load factor of 0.8.

    • IntMap

      public IntMap(int initialCapacity)
      Creates a new map with a load factor of 0.8.
      Parameters:
      initialCapacity - If not a power of two, it is increased to the next nearest power of two.

    • IntMap

      public IntMap(int initialCapacity, float loadFactor)
      Creates a new map with the specified initial capacity and load factor. This map will hold initialCapacity items before growing the backing table.
      Parameters:
      initialCapacity - If not a power of two, it is increased to the next nearest power of two.

    • IntMap

      public IntMap(IntMap<? extends V> map)
      Creates a new map identical to the specified map.

  • Method Details

    • of

      public static <V> IntMap<V> of(Object... values)

    • put

      public V put(int key, V value)

    • putAll

      public void putAll(IntMap<? extends V> map)

    • get

      public V get(int key, Prov<V> defaultValue)

    • get

      public V get(int key)

    • get

      public V get(int key, V defaultValue)

    • remove

      public V remove(int key)

    • isEmpty

      public boolean isEmpty()
      Returns true if the map is empty.

    • shrink

      public void shrink(int maximumCapacity)
      Reduces the size of the backing arrays to be the specified capacity or less. If the capacity is already less, nothing is done. If the map contains more items than the specified capacity, the next highest power of two capacity is used instead.

    • clear

      public void clear(int maximumCapacity)
      Clears the map and reduces the size of the backing arrays to be the specified capacity if they are larger.

    • clear

      public void clear()

    • containsValue

      public boolean containsValue(Object value, boolean identity)
      Returns true if the specified value is in the map. Note this traverses the entire map and compares every value, which may be an expensive operation.
      Parameters:
      identity - If true, uses == to compare the specified value with values in the map. If false, uses equals(Object).

    • containsKey

      public boolean containsKey(int key)

    • findKey

      public int findKey(Object value, boolean identity, int notFound)
      Returns the key for the specified value, or notFound if it is not in the map. Note this traverses the entire map and compares every value, which may be an expensive operation.
      Parameters:
      identity - If true, uses == to compare the specified value with values in the map. If false, uses equals(Object).

    • ensureCapacity

      public void ensureCapacity(int additionalCapacity)
      Increases the size of the backing array to accommodate the specified number of additional items. Useful before adding many items to avoid multiple backing array resizes.

    • hashCode

      public int hashCode()
      Overrides:
      hashCode in class Object

    • equals

      public boolean equals(Object obj)
      Overrides:
      equals in class Object

    • toString

      public String toString()
      Overrides:
      toString in class Object

    • iterator

      public Iterator<IntMap.Entry<V>> iterator()
      Specified by:
      iterator in interface Iterable<V>

    • entries

      public IntMap.Entries<V> entries()
      Returns an iterator for the entries in the map. Remove is supported. Note that the same iterator instance is returned each time this method is called. Use the IntMap.Entries constructor for nested or multithreaded iteration.

    • values

      public IntMap.Values<V> values()
      Returns an iterator for the values in the map. Remove is supported. Note that the same iterator instance is returned each time this method is called. Use the IntMap.Entries constructor for nested or multithreaded iteration.

    • keys

      public IntMap.Keys keys()
      Returns an iterator for the keys in the map. Remove is supported. Note that the same iterator instance is returned each time this method is called. Use the IntMap.Entries constructor for nested or multithreaded iteration.