Class ObjectMap<K,​V>


  • public class ObjectMap<K,​V>
    extends java.lang.Object
    An unordered map. This implementation is a cuckoo hash map using 3 hashes, random walking, and a small stash for problematic keys. Null keys are not allowed. 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.
    • Field Summary

      Fields 
      Modifier and Type Field Description
      int size  
    • Constructor Summary

      Constructors 
      Constructor Description
      ObjectMap()
      Creates a new map with an initial capacity of 32 and a load factor of 0.8.
      ObjectMap​(int initialCapacity)
      Creates a new map with a load factor of 0.8.
      ObjectMap​(int initialCapacity, float loadFactor)
      Creates a new map with the specified initial capacity and load factor.
    • Method Summary

      All Methods Static Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      void clear()  
      boolean containsKey​(K key)  
      boolean containsValue​(java.lang.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 acommodate the specified number of additional items.
      ObjectMap.Entries<K,​V> entries()
      Returns an iterator for the entries in the map.
      K findKey​(java.lang.Object value, boolean identity)
      Returns the key for the specified value, or null if it is not in the map.
      V get​(K key)  
      ObjectMap.Keys<K> keys()
      Returns an iterator for the keys in the map.
      static int nextPowerOfTwo​(int value)  
      V put​(K key, V value)
      Returns the old value associated with the specified key, or null.
      void putAll​(ObjectMap<K,​V> map)  
      V remove​(K key)  
      java.lang.String toString()  
      ObjectMap.Values<V> values()
      Returns an iterator for the values in the map.
      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
    • Field Detail

      • size

        public int size
    • Constructor Detail

      • ObjectMap

        public ObjectMap()
        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.
      • ObjectMap

        public ObjectMap​(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.
      • ObjectMap

        public ObjectMap​(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.
    • Method Detail

      • put

        public V put​(K key,
                     V value)
        Returns the old value associated with the specified key, or null.
      • putAll

        public void putAll​(ObjectMap<K,​V> map)
      • get

        public V get​(K key)
      • remove

        public V remove​(K key)
      • clear

        public void clear()
      • containsValue

        public boolean containsValue​(java.lang.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​(K key)
      • findKey

        public K findKey​(java.lang.Object value,
                         boolean identity)
        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.
        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.
      • toString

        public java.lang.String toString()
        Overrides:
        toString in class java.lang.Object
      • entries

        public ObjectMap.Entries<K,​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 ObjectMap.Entries constructor for nested or multithreaded iteration.
      • values

        public ObjectMap.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 ObjectMap.Entries constructor for nested or multithreaded iteration.
      • keys

        public ObjectMap.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 ObjectMap.Entries constructor for nested or multithreaded iteration.
      • nextPowerOfTwo

        public static int nextPowerOfTwo​(int value)