Package arc.struct

Class ObjectIntMap<K>

java.lang.Object
arc.struct.ObjectIntMap<K>
All Implemented Interfaces:
Iterable<ObjectIntMap.Entry<K>>
public class ObjectIntMap<K> extends Object implements Iterable<ObjectIntMap.Entry<K>>
An unordered map where the values are ints. This implementation is a cuckoo hash map using 3 hashes, random walking, and a small stash for problematic keys. Null keys are not 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.

  • Field Details

    • size

      public int size

  • Constructor Details

    • ObjectIntMap

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

    • ObjectIntMap

      public ObjectIntMap(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.

    • ObjectIntMap

      public ObjectIntMap(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.

    • ObjectIntMap

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

  • Method Details

    • put

      public void put(K key, int value)

    • putAll

      public void putAll(ObjectIntMap<? extends K> map)

    • putAll

      public void putAll(Object... values)

    • get

      public int get(K key)

    • get

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

    • increment

      public int increment(K key)

    • increment

      public int increment(K key, int amount)

    • increment

      public int increment(K 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(K key)
      Returns:
      0 as default value.

    • remove

      public int remove(K key, int defaultValue)
      Returns:
      the value that was removed, or 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(K key)

    • findKey

      public K findKey(int value)
      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 ObjectIntMap.Entries<K> iterator()
      Specified by:
      iterator in interface Iterable<K>

    • entries

      public ObjectIntMap.Entries<K> 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 ObjectIntMap.Entries constructor for nested or multithreaded iteration.

    • values

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

    • keys

      public ObjectIntMap.Keys<K> 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 ObjectIntMap.Entries constructor for nested or multithreaded iteration.