Class IntMap<V>


  • public class IntMap<V>
    extends Object
    An unordered map that uses int keys. This implementation is a cuckoo hash map using 3 hashes (if table size is less than 2^16) or 4 hashes (if table size is greater than or equal to 2^16), 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.
    Author:
    Nathan Sweet
    • 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 32 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.
    • Field Detail

      • size

        public int size
    • Constructor Detail

      • IntMap

        public IntMap()
        Creates a new map with an initial capacity of 32 and a load factor of 0.8. This map will hold 25 items before growing the backing table.
      • IntMap

        public IntMap​(int initialCapacity)
        Creates a new map with a load factor of 0.8. This map will hold initialCapacity * 0.8 items before growing the backing table.
      • IntMap

        public IntMap​(int initialCapacity,
                      float loadFactor)
        Creates a new map with the specified initial capacity and load factor. This map will hold initialCapacity * loadFactor items before growing the backing table.
      • IntMap

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

      • put

        public V put​(int key,
                     V value)
      • putAll

        public void putAll​(IntMap<V> map)
      • get

        public V get​(int key)
      • get

        public V get​(int key,
                     V defaultValue)
      • remove

        public V remove​(int key)
      • 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 Object.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 Object.equals(Object).
      • ensureCapacity

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