Interface Object2ObjectMap<K,​V>

All Superinterfaces:
Function<K,​V>, java.util.function.Function<K,​V>, java.util.Map<K,​V>, Object2ObjectFunction<K,​V>
All Known Subinterfaces:
Object2ObjectSortedMap<K,​V>
All Known Implementing Classes:
AbstractObject2ObjectMap, AbstractObject2ObjectSortedMap, Object2ObjectArrayMap, Object2ObjectAVLTreeMap, Object2ObjectLinkedOpenCustomHashMap, Object2ObjectLinkedOpenHashMap, Object2ObjectMaps.EmptyMap, Object2ObjectMaps.Singleton, Object2ObjectMaps.SynchronizedMap, Object2ObjectMaps.UnmodifiableMap, Object2ObjectOpenCustomHashMap, Object2ObjectOpenHashMap, Object2ObjectRBTreeMap, Object2ObjectSortedMaps.EmptySortedMap, Object2ObjectSortedMaps.Singleton, Object2ObjectSortedMaps.SynchronizedSortedMap, Object2ObjectSortedMaps.UnmodifiableSortedMap

public interface Object2ObjectMap<K,​V>
extends Object2ObjectFunction<K,​V>, java.util.Map<K,​V>
A type-specific Map; provides some additional methods that use polymorphism to avoid (un)boxing, and handling of a default return value.

Besides extending the corresponding type-specific function, this interface strengthens Map.entrySet(), keySet() and values(). Moreover, a number of methods, such as size(), defaultReturnValue(), etc., are un-defaulted as their function default do not make sense for a map. Maps returning entry sets of type Object2ObjectMap.FastEntrySet support also fast iteration.

A submap or subset may or may not have an independent default return value (which however must be initialized to the default return value of the originator).

See Also:
Map
  • Nested Class Summary

    Nested Classes
    Modifier and Type Interface Description
    static interface  Object2ObjectMap.Entry<K,​V>
    A type-specific Map.Entry; provides some additional methods that use polymorphism to avoid (un)boxing.
    static interface  Object2ObjectMap.FastEntrySet<K,​V>
    An entry set providing fast iteration.
  • Method Summary

    Modifier and Type Method Description
    default void clear()
    Removes all of the mappings from this map (optional operation).
    default V compute​(K key, java.util.function.BiFunction<? super K,​? super V,​? extends V> remappingFunction)
    Attempts to compute a mapping for the specified key and its current mapped value (or null if there is no current mapping).
    default V computeIfAbsent​(K key, Object2ObjectFunction<? super K,​? extends V> mappingFunction)
    If the specified key is not already associated with a value, attempts to compute its value using the given mapping function and enters it into this map, unless the key is not present in the given mapping function.
    default V computeIfPresent​(K key, java.util.function.BiFunction<? super K,​? super V,​? extends V> remappingFunction)
    If the value for the specified key is present, attempts to compute a new mapping given the key and its current mapped value.
    default V computeObjectIfAbsentPartial​(K key, Object2ObjectFunction<? super K,​? extends V> mappingFunction)
    Deprecated.
    Please use computeIfAbsent() instead.
    boolean containsKey​(java.lang.Object key)
    Returns true if this function contains a mapping for the specified key.
    V defaultReturnValue()
    Gets the default return value.
    void defaultReturnValue​(V rv)
    Sets the default return value (optional operation).
    default ObjectSet<java.util.Map.Entry<K,​V>> entrySet()
    Returns a set view of the mappings contained in this map.
    default void forEach​(java.util.function.BiConsumer<? super K,​? super V> consumer)  
    default V getOrDefault​(java.lang.Object key, V defaultValue)
    Returns the value to which the specified key is mapped, or the defaultValue if this map contains no mapping for the key.
    ObjectSet<K> keySet()
    default V merge​(K key, V value, java.util.function.BiFunction<? super V,​? super V,​? extends V> remappingFunction)
    If the specified key is not already associated with a value, associates it with the given value.
    ObjectSet<Object2ObjectMap.Entry<K,​V>> object2ObjectEntrySet()
    Returns a type-specific set view of the mappings contained in this map.
    default V put​(K key, V value)
    Adds a pair to the map (optional operation).
    default V putIfAbsent​(K key, V value)
    If the specified key is not already associated with a value, associates it with the given value and returns the default return value, else returns the current value.
    default V remove​(java.lang.Object key)
    Removes the mapping with the given key (optional operation).
    default boolean remove​(java.lang.Object key, java.lang.Object value)
    Removes the entry for the specified key only if it is currently mapped to the specified value.
    default V replace​(K key, V value)
    Replaces the entry for the specified key only if it is currently mapped to some value.
    default boolean replace​(K key, V oldValue, V newValue)
    Replaces the entry for the specified key only if currently mapped to the specified value.
    int size()
    Returns the number of key/value mappings in this map.
    ObjectCollection<V> values()

    Methods inherited from interface it.unimi.dsi.fastutil.Function

    apply

    Methods inherited from interface java.util.function.Function

    andThen, compose

    Methods inherited from interface java.util.Map

    computeIfAbsent, containsValue, equals, get, hashCode, isEmpty, putAll, replaceAll
  • Method Details

    • size

      int size()
      Returns the number of key/value mappings in this map. If the map contains more than Integer.MAX_VALUE elements, returns Integer.MAX_VALUE.
      Specified by:
      size in interface Function<K,​V>
      Specified by:
      size in interface java.util.Map<K,​V>
      Returns:
      the number of key-value mappings in this map.
      See Also:
      Size64
    • clear

      default void clear()
      Removes all of the mappings from this map (optional operation). The map will be empty after this call returns.
      Specified by:
      clear in interface Function<K,​V>
      Specified by:
      clear in interface java.util.Map<K,​V>
      Throws:
      java.lang.UnsupportedOperationException - if the clear() operation is not supported by this map
      See Also:
      Map.clear()
    • defaultReturnValue

      void defaultReturnValue​(V rv)
      Sets the default return value (optional operation). This value must be returned by type-specific versions of get(), put() and remove() to denote that the map does not contain the specified key. It must be null by default.

      Warning: Changing this to a non-null value can have unforeseen consequences. Especially, it breaks compatibility with the specifications of Java's Map interface. It has to be used with great care and thorough study of all method comments is recommended.

      Specified by:
      defaultReturnValue in interface Object2ObjectFunction<K,​V>
      Parameters:
      rv - the new default return value.
      See Also:
      defaultReturnValue()
    • defaultReturnValue

      V defaultReturnValue()
      Gets the default return value.
      Specified by:
      defaultReturnValue in interface Object2ObjectFunction<K,​V>
      Returns:
      the current default return value.
    • object2ObjectEntrySet

      ObjectSet<Object2ObjectMap.Entry<K,​V>> object2ObjectEntrySet()
      Returns a type-specific set view of the mappings contained in this map.

      This method is necessary because there is no inheritance along type parameters: it is thus impossible to strengthen Map.entrySet() so that it returns an ObjectSet of type-specific entries (the latter makes it possible to access keys and values with type-specific methods).

      Returns:
      a type-specific set view of the mappings contained in this map.
      See Also:
      Map.entrySet()
    • entrySet

      default ObjectSet<java.util.Map.Entry<K,​V>> entrySet()
      Returns a set view of the mappings contained in this map.
      Specified by:
      entrySet in interface java.util.Map<K,​V>
      Returns:
      a set view of the mappings contained in this map.
      See Also:
      Map.entrySet()
      API Notes:
      Note that this specification strengthens the one given in Map.entrySet().
    • put

      default V put​(K key, V value)
      Adds a pair to the map (optional operation).

      This default implementation just delegates to the corresponding function method.

      Specified by:
      put in interface Function<K,​V>
      Specified by:
      put in interface java.util.Map<K,​V>
      Specified by:
      put in interface Object2ObjectFunction<K,​V>
      Parameters:
      key - the key.
      value - the value.
      Returns:
      the old value, or the default return value if no value was present for the given key.
      See Also:
      Function.put(Object,Object)
    • remove

      default V remove​(java.lang.Object key)
      Removes the mapping with the given key (optional operation).

      This default implementation just delegates to the corresponding type-specific–function method.

      Specified by:
      remove in interface Function<K,​V>
      Specified by:
      remove in interface java.util.Map<K,​V>
      Specified by:
      remove in interface Object2ObjectFunction<K,​V>
      Parameters:
      key - the key.
      Returns:
      the old value, or the default return value if no value was present for the given key.
      See Also:
      Function.remove(Object)
    • keySet

      ObjectSet<K> keySet()
      Specified by:
      keySet in interface java.util.Map<K,​V>
      Returns:
      a set view of the keys contained in this map.
      See Also:
      Map.keySet()
      API Notes:
      Note that this specification strengthens the one given in Map.keySet().
    • values

      ObjectCollection<V> values()
      Specified by:
      values in interface java.util.Map<K,​V>
      Returns:
      a set view of the values contained in this map.
      See Also:
      Map.values()
      API Notes:
      Note that this specification strengthens the one given in Map.values().
    • containsKey

      boolean containsKey​(java.lang.Object key)
      Returns true if this function contains a mapping for the specified key.
      Specified by:
      containsKey in interface Function<K,​V>
      Specified by:
      containsKey in interface java.util.Map<K,​V>
      Parameters:
      key - the key.
      Returns:
      true if this function associates a value to key.
      See Also:
      Map.containsKey(Object)
    • forEach

      default void forEach​(java.util.function.BiConsumer<? super K,​? super V> consumer)
      Specified by:
      forEach in interface java.util.Map<K,​V>
    • getOrDefault

      default V getOrDefault​(java.lang.Object key, V defaultValue)
      Returns the value to which the specified key is mapped, or the defaultValue if this map contains no mapping for the key.
      Specified by:
      getOrDefault in interface Function<K,​V>
      Specified by:
      getOrDefault in interface java.util.Map<K,​V>
      Specified by:
      getOrDefault in interface Object2ObjectFunction<K,​V>
      Parameters:
      key - the key.
      defaultValue - the default mapping of the key.
      Returns:
      the value to which the specified key is mapped, or the defaultValue if this map contains no mapping for the key.
      Since:
      8.0.0
      See Also:
      Map.getOrDefault(Object, Object)
    • putIfAbsent

      default V putIfAbsent​(K key, V value)
      If the specified key is not already associated with a value, associates it with the given value and returns the default return value, else returns the current value.
      Specified by:
      putIfAbsent in interface java.util.Map<K,​V>
      Parameters:
      key - key with which the specified value is to be associated.
      value - value to be associated with the specified key.
      Returns:
      the previous value associated with the specified key, or the default return value if there was no mapping for the key.
      Since:
      8.0.0
      See Also:
      Map.putIfAbsent(Object, Object)
    • remove

      default boolean remove​(java.lang.Object key, java.lang.Object value)
      Removes the entry for the specified key only if it is currently mapped to the specified value.
      Specified by:
      remove in interface java.util.Map<K,​V>
      Parameters:
      key - key with which the specified value is associated.
      value - value expected to be associated with the specified key.
      Returns:
      true if the value was removed.
      Since:
      8.0.0
      See Also:
      Map.remove(Object, Object)
    • replace

      default boolean replace​(K key, V oldValue, V newValue)
      Replaces the entry for the specified key only if currently mapped to the specified value.
      Specified by:
      replace in interface java.util.Map<K,​V>
      Parameters:
      key - key with which the specified value is associated.
      oldValue - value expected to be associated with the specified key.
      newValue - value to be associated with the specified key.
      Returns:
      true if the value was replaced.
      Since:
      8.0.0
      See Also:
      Map.replace(Object, Object, Object)
    • replace

      default V replace​(K key, V value)
      Replaces the entry for the specified key only if it is currently mapped to some value.
      Specified by:
      replace in interface java.util.Map<K,​V>
      Parameters:
      key - key with which the specified value is associated.
      value - value to be associated with the specified key.
      Returns:
      the previous value associated with the specified key, or the default return value if there was no mapping for the key.
      Since:
      8.0.0
      See Also:
      Map.replace(Object, Object)
    • computeIfAbsent

      default V computeIfAbsent​(K key, Object2ObjectFunction<? super K,​? extends V> mappingFunction)
      If the specified key is not already associated with a value, attempts to compute its value using the given mapping function and enters it into this map, unless the key is not present in the given mapping function.

      This version of computeIfAbsent() uses a type-specific version of fastutil's Function. Since Function has a containsKey() method, it is possible to avoid adding a key by having containsKey() return false for that key.

      Parameters:
      key - key with which the specified value is to be associated.
      mappingFunction - the function to compute a value.
      Returns:
      the current (existing or computed) value associated with the specified key.
      Since:
      8.0.0
      See Also:
      Map.computeIfAbsent(Object, java.util.function.Function)
      API Notes:
      all computeIfAbsent() methods have a different logic based on the argument; no delegation is performed, contrarily to other superficially similar methods such as Iterator.forEachRemaining(java.util.function.Consumer<? super E>) or List.replaceAll(java.util.function.UnaryOperator<E>).
    • computeObjectIfAbsentPartial

      @Deprecated default V computeObjectIfAbsentPartial​(K key, Object2ObjectFunction<? super K,​? extends V> mappingFunction)
      Deprecated.
      Please use computeIfAbsent() instead.
    • computeIfPresent

      default V computeIfPresent​(K key, java.util.function.BiFunction<? super K,​? super V,​? extends V> remappingFunction)
      If the value for the specified key is present, attempts to compute a new mapping given the key and its current mapped value.
      Specified by:
      computeIfPresent in interface java.util.Map<K,​V>
      Parameters:
      key - key with which the specified value is to be associated.
      remappingFunction - the function to compute a value.
      Returns:
      the new value associated with the specified key, or the default return value if none.
      Since:
      8.0.0
      See Also:
      Map.computeIfPresent(Object, java.util.function.BiFunction)
    • compute

      default V compute​(K key, java.util.function.BiFunction<? super K,​? super V,​? extends V> remappingFunction)
      Attempts to compute a mapping for the specified key and its current mapped value (or null if there is no current mapping).

      If the function returns null, the mapping is removed (or remains absent if initially absent). If the function itself throws an (unchecked) exception, the exception is rethrown, and the current mapping is left unchanged.

      Specified by:
      compute in interface java.util.Map<K,​V>
      Parameters:
      key - key with which the specified value is to be associated.
      remappingFunction - the function to compute a value.
      Returns:
      the new value associated with the specified key, or the default return value if none.
      Since:
      8.0.0
      See Also:
      Map.compute(Object, java.util.function.BiFunction)
    • merge

      default V merge​(K key, V value, java.util.function.BiFunction<? super V,​? super V,​? extends V> remappingFunction)
      If the specified key is not already associated with a value, associates it with the given value. Otherwise, replaces the associated value with the results of the given remapping function, or removes if the result is null.
      Specified by:
      merge in interface java.util.Map<K,​V>
      Parameters:
      key - key with which the resulting value is to be associated.
      value - the value to be merged with the existing value associated with the key or, if no existing value is associated with the key, to be associated with the key.
      remappingFunction - the function to recompute a value if present.
      Returns:
      the new value associated with the specified key, or the default return value if no value is associated with the key.
      Since:
      8.0.0
      See Also:
      Map.merge(Object, Object, java.util.function.BiFunction)
      API Notes:
      The JDK specification for this method equates not being associated with a value with being associated with {code null}. This is not the case for this method.