Package arc.struct

Class ObjectMap<K,V>

java.lang.Object
arc.struct.ObjectMap<K,V>
All Implemented Interfaces:
Iterable<ObjectMap.Entry<K,V>>
Direct Known Subclasses:
OrderedMap, StringMap
public class ObjectMap<K,V> extends Object implements Iterable<ObjectMap.Entry<K,V>>
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.

Iteration can be very slow for a map with a large capacity. clear(int) and shrink(int) can be used to reduce the capacity. OrderedMap provides much faster iteration.

  • Nested Class Summary

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

  • 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 51 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.
    ObjectMap(ObjectMap<? extends K,? extends V> map)
    Creates a new map identical to the specified map.

  • Method Summary

    Modifier and Type
    Method
    Description
    void
    clear()
    Clears the map, leaving the backing arrays at the current capacity.
    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(K key)
     
    boolean
    containsValue(Object value, boolean identity)
    Returns true if the specified value is in the map.
    ObjectMap<K,V>
    copy()
     
    void
    each(Cons2<K,V> cons)
    Iterates through key/value pairs.
    void
    ensureCapacity(int additionalCapacity)
    Increases the size of the backing array to accommodate the specified number of additional items.
    ObjectMap.Entries<K,V>
    entries()
    Returns an iterator for the entries in the map.
    boolean
    equals(Object obj)
     
    K
    findKey(Object value, boolean identity)
    Returns the key for the specified value, or null if it is not in the map.
    V
    get(K key)
    Returns the value for the specified key, or null if the key is not in the map.
    V
    get(K key, Prov<V> supplier)
    Tries to get the value.
    V
    get(K key, V defaultValue)
    Returns the value for the specified key, or the default value if the key is not in the map.
    V
    getNull(K key)
    Get, with a nullable key.
    V
    getThrow(K key, Prov<? extends RuntimeException> error)
     
    int
    hashCode()
     
    boolean
    isEmpty()
    Returns true if the map is empty.
    ObjectMap.Entries<K,V>
    iterator()
     
    ObjectMap.Keys<K>
    keys()
    Returns an iterator for the keys in the map.
    ObjectMap<K,V>
    merge(ObjectMap<? extends K,? extends V> map)
    Put all the keys of this other map into this map, and return this map for chaining.
    static <K, V> ObjectMap<K,V>
    of(Object... values)
     
    V
    put(K key, V value)
    Returns the old value associated with the specified key, or null.
    void
    putAll(ObjectMap<? extends K,? extends V> map)
     
    void
    putAll(Object... values)
     
    V
    remove(K key)
    Returns the value associated with the key, or null.
    void
    shrink(int maximumCapacity)
    Reduces the size of the backing arrays to be the specified capacity or less.
    String
    toString()
     
    String
    toString(String separator)
     
    String
    toString(String separator, boolean braces)
     
    ObjectMap.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

    • ObjectMap

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

    • ObjectMap

      public ObjectMap(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.

    • ObjectMap

      public ObjectMap(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.

    • ObjectMap

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

  • Method Details

    • of

      public static <K, V> ObjectMap<K,V> of(Object... values)

    • each

      public void each(Cons2<K,V> cons)
      Iterates through key/value pairs.

    • copy

      public ObjectMap<K,V> copy()

    • put

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

    • putAll

      public void putAll(ObjectMap<? extends K,? extends V> map)

    • putAll

      public void putAll(Object... values)

    • merge

      public ObjectMap<K,V> merge(ObjectMap<? extends K,? extends V> map)
      Put all the keys of this other map into this map, and return this map for chaining.

    • getThrow

      public V getThrow(K key, Prov<? extends RuntimeException> error)

    • get

      public V get(K key, Prov<V> supplier)
      Tries to get the value. If it does not exist, it creates a new instance using the supplier and places it, returning the value.

    • getNull

      public V getNull(K key)
      Get, with a nullable key.

    • get

      public V get(K key)
      Returns the value for the specified key, or null if the key is not in the map.

    • get

      public V get(K key, V defaultValue)
      Returns the value for the specified key, or the default value if the key is not in the map.

    • remove

      public V remove(K key)
      Returns the value associated with the key, or null.

    • 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. The reduction is done by allocating new arrays, though for large arrays this can be faster than clearing the existing array.

    • clear

      public void clear()
      Clears the map, leaving the backing arrays at the current capacity. When the capacity is high and the population is low, iteration can be unnecessarily slow. clear(int) can be used to reduce the capacity.

    • 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(K key)

    • findKey

      public K findKey(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 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(String separator)

    • toString

      public String toString()
      Overrides:
      toString in class Object

    • toString

      public String toString(String separator, boolean braces)

    • iterator

      public ObjectMap.Entries<K,V> iterator()
      Specified by:
      iterator in interface Iterable<K>

    • 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.Values 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.Keys constructor for nested or multithreaded iteration.