Package arc.struct

Class IntIntMap

java.lang.Object
arc.struct.IntIntMap
All Implemented Interfaces:
Iterable<IntIntMap.Entry>
public class IntIntMap extends Object implements Iterable<IntIntMap.Entry>
An unordered map where the keys and values are ints. This implementation is a cuckoo hash map using 3 hashes, random walking, and a small stash for problematic keys. 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 
    IntIntMap.Entries
     
    static class 
    IntIntMap.Entry
     
    static class 
    IntIntMap.Keys
     
    static class 
    IntIntMap.Values
     

  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    int
    size
     

  • Constructor Summary

    Constructors
    Constructor
    Description
    IntIntMap()
    Creates a new map with an initial capacity of 51 and a load factor of 0.8.
    IntIntMap(int initialCapacity)
    Creates a new map with a load factor of 0.8.
    IntIntMap(int initialCapacity, float loadFactor)
    Creates a new map with the specified initial capacity and load factor.
    IntIntMap(IntIntMap 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(int value)
    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.
    IntIntMap.Entries
    entries()
    Returns an iterator for the entries in the map.
    boolean
    equals(Object obj)
     
    int
    findKey(int value, int notFound)
    Returns the key for the specified value, or null if it is not in the map.
    int
    get(int key)
     
    int
    get(int key, int defaultValue)
     
    int
    getOrPut(int key, int value)
    Only inserts into the map if value is not present.
    int
    hashCode()
     
    int
    increment(int key)
     
    int
    increment(int key, int amount)
     
    int
    increment(int key, int defaultValue, int increment)
    Returns the key's current value and increments the stored value.
    boolean
    isEmpty()
    Returns true if the map is empty.
    Iterator<IntIntMap.Entry>
    iterator()
     
    IntIntMap.Keys
    keys()
    Returns an iterator for the keys in the map.
    static IntIntMap
    of(int... values)
     
    void
    put(int key, int value)
     
    void
    putAll(IntIntMap map)
     
    int
    remove(int key)
     
    int
    remove(int key, int defaultValue)
     
    void
    shrink(int maximumCapacity)
    Reduces the size of the backing arrays to be the specified capacity or less.
    String
    toString()
     
    IntIntMap.Values
    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

    • IntIntMap

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

    • IntIntMap

      public IntIntMap(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.

    • IntIntMap

      public IntIntMap(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.

    • IntIntMap

      public IntIntMap(IntIntMap map)
      Creates a new map identical to the specified map.

  • Method Details

    • of

      public static IntIntMap of(int... values)

    • put

      public void put(int key, int value)

    • putAll

      public void putAll(IntIntMap map)

    • get

      public int get(int key)

    • get

      public int get(int key, int defaultValue)
      Parameters:
      defaultValue - Returned if the key was not associated with a value.

    • getOrPut

      public int getOrPut(int key, int value)
      Only inserts into the map if value is not present.
      Parameters:
      key - The key.
      value - The value.
      Returns:
      The associated value if key is present in the map, else value.

    • increment

      public int increment(int key)

    • increment

      public int increment(int key, int amount)

    • increment

      public int increment(int key, int defaultValue, int increment)
      Returns the key's current value and increments the stored value. If the key is not in the map, defaultValue + increment is put into the map.

    • remove

      public int remove(int key)

    • remove

      public int remove(int key, int defaultValue)

    • 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(int value)
      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.

    • containsKey

      public boolean containsKey(int key)

    • findKey

      public int findKey(int value, int notFound)
      Returns the key for the specified value, or null if it is not in the map. Note this traverses the entire map and compares every value, which may be an expensive operation.

    • 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<IntIntMap.Entry> iterator()
      Specified by:
      iterator in interface Iterable<IntIntMap.Entry>

    • entries

      public IntIntMap.Entries 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 IntIntMap.Entries constructor for nested or multithreaded iteration.

    • values

      public IntIntMap.Values 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 IntIntMap.Entries constructor for nested or multithreaded iteration.

    • keys

      public IntIntMap.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 IntIntMap.Entries constructor for nested or multithreaded iteration.