Class Short2ShortLinkedOpenHashMap

All Implemented Interfaces:
Function<Short,​Short>, Hash, Short2ShortFunction, Short2ShortMap, Short2ShortSortedMap, Serializable, Cloneable, Function<Short,​Short>, IntUnaryOperator, Map<Short,​Short>, SortedMap<Short,​Short>

public class Short2ShortLinkedOpenHashMap
extends AbstractShort2ShortSortedMap
implements Serializable, Cloneable, Hash
A type-specific linked hash map with with a fast, small-footprint implementation.

Instances of this class use a hash table to represent a map. The table is filled up to a specified load factor, and then doubled in size to accommodate new entries. If the table is emptied below one fourth of the load factor, it is halved in size; however, the table is never reduced to a size smaller than that at creation time: this approach makes it possible to create maps with a large capacity in which insertions and deletions do not cause immediately rehashing. Moreover, halving is not performed when deleting entries from an iterator, as it would interfere with the iteration process.

Note that clear() does not modify the hash table size. Rather, a family of trimming methods lets you control the size of the table; this is particularly useful if you reuse instances of this class.

Iterators generated by this map will enumerate pairs in the same order in which they have been added to the map (addition of pairs whose key is already present in the map does not change the iteration order). Note that this order has nothing in common with the natural order of the keys. The order is kept by means of a doubly linked list, represented via an array of longs parallel to the table.

This class implements the interface of a sorted map, so to allow easy access of the iteration order: for instance, you can get the first key in iteration order with firstKey() without having to create an iterator; however, this class partially violates the SortedMap contract because all submap methods throw an exception and comparator() returns always null.

Additional methods, such as getAndMoveToFirst(), make it easy to use instances of this class as a cache (e.g., with LRU policy).

The iterators provided by the views of this class using are type-specific list iterators, and can be started at any element which is a key of the map, or a NoSuchElementException exception will be thrown. If, however, the provided element is not the first or last key in the map, the first access to the list index will require linear time, as in the worst case the entire key set must be scanned in iteration order to retrieve the positional index of the starting key. If you use just the methods of a type-specific BidirectionalIterator, however, all operations will be performed in constant time.

See Also:
Hash, HashCommon, Serialized Form
  • Constructor Details

  • Method Details

    • putAll

      public void putAll​(Map<? extends Short,​? extends Short> m)
      Description copied from class: AbstractShort2ShortMap
      Specified by:
      putAll in interface Map<Short,​Short>
      Overrides:
      putAll in class AbstractShort2ShortMap
    • put

      public short put​(short k, short v)
      Description copied from interface: Short2ShortFunction
      Adds a pair to the map (optional operation).
      Specified by:
      put in interface Short2ShortFunction
      Parameters:
      k - the key.
      v - 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)
    • addTo

      public short addTo​(short k, short incr)
      Adds an increment to value currently associated with a key.

      Note that this method respects the default return value semantics: when called with a key that does not currently appears in the map, the key will be associated with the default return value plus the given increment.

      Parameters:
      k - the key.
      incr - the increment.
      Returns:
      the old value, or the default return value if no value was present for the given key.
    • remove

      public short remove​(short k)
      Description copied from interface: Short2ShortFunction
      Removes the mapping with the given key (optional operation).
      Specified by:
      remove in interface Short2ShortFunction
      Parameters:
      k - 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)
    • removeFirstShort

      public short removeFirstShort()
      Removes the mapping associated with the first key in iteration order.
      Returns:
      the value previously associated with the first key in iteration order.
      Throws:
      NoSuchElementException - is this map is empty.
    • removeLastShort

      public short removeLastShort()
      Removes the mapping associated with the last key in iteration order.
      Returns:
      the value previously associated with the last key in iteration order.
      Throws:
      NoSuchElementException - is this map is empty.
    • getAndMoveToFirst

      public short getAndMoveToFirst​(short k)
      Returns the value to which the given key is mapped; if the key is present, it is moved to the first position of the iteration order.
      Parameters:
      k - the key.
      Returns:
      the corresponding value, or the default return value if no value was present for the given key.
    • getAndMoveToLast

      public short getAndMoveToLast​(short k)
      Returns the value to which the given key is mapped; if the key is present, it is moved to the last position of the iteration order.
      Parameters:
      k - the key.
      Returns:
      the corresponding value, or the default return value if no value was present for the given key.
    • putAndMoveToFirst

      public short putAndMoveToFirst​(short k, short v)
      Adds a pair to the map; if the key is already present, it is moved to the first position of the iteration order.
      Parameters:
      k - the key.
      v - the value.
      Returns:
      the old value, or the default return value if no value was present for the given key.
    • putAndMoveToLast

      public short putAndMoveToLast​(short k, short v)
      Adds a pair to the map; if the key is already present, it is moved to the last position of the iteration order.
      Parameters:
      k - the key.
      v - the value.
      Returns:
      the old value, or the default return value if no value was present for the given key.
    • get

      public short get​(short k)
      Description copied from interface: Short2ShortFunction
      Returns the value to which the given key is mapped.
      Specified by:
      get in interface Short2ShortFunction
      Parameters:
      k - the key.
      Returns:
      the corresponding value, or the default return value if no value was present for the given key.
      See Also:
      Function.get(Object)
    • containsKey

      public boolean containsKey​(short k)
      Description copied from interface: Short2ShortMap
      Returns true if this function contains a mapping for the specified key.
      Specified by:
      containsKey in interface Short2ShortFunction
      Specified by:
      containsKey in interface Short2ShortMap
      Overrides:
      containsKey in class AbstractShort2ShortMap
      Parameters:
      k - the key.
      Returns:
      true if this function associates a value to key.
      See Also:
      Map.containsKey(Object)
    • containsValue

      public boolean containsValue​(short v)
      Description copied from interface: Short2ShortMap
      Returns true if this map maps one or more keys to the specified value.
      Specified by:
      containsValue in interface Short2ShortMap
      Overrides:
      containsValue in class AbstractShort2ShortMap
      See Also:
      Map.containsValue(Object)
    • getOrDefault

      public short getOrDefault​(short k, short 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 Short2ShortMap
      Parameters:
      k - 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.
      See Also:
      Map.getOrDefault(Object, Object)
    • putIfAbsent

      public short putIfAbsent​(short k, short v)
      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 Short2ShortMap
      Parameters:
      k - key with which the specified value is to be associated.
      v - 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.
      See Also:
      Map.putIfAbsent(Object, Object)
    • remove

      public boolean remove​(short k, short v)
      Removes the entry for the specified key only if it is currently mapped to the specified value.
      Specified by:
      remove in interface Short2ShortMap
      Parameters:
      k - key with which the specified value is associated.
      v - value expected to be associated with the specified key.
      Returns:
      true if the value was removed.
      See Also:
      Map.remove(Object, Object)
    • replace

      public boolean replace​(short k, short oldValue, short v)
      Replaces the entry for the specified key only if currently mapped to the specified value.
      Specified by:
      replace in interface Short2ShortMap
      Parameters:
      k - key with which the specified value is associated.
      oldValue - value expected to be associated with the specified key.
      v - value to be associated with the specified key.
      Returns:
      true if the value was replaced.
      See Also:
      Map.replace(Object, Object, Object)
    • replace

      public short replace​(short k, short v)
      Replaces the entry for the specified key only if it is currently mapped to some value.
      Specified by:
      replace in interface Short2ShortMap
      Parameters:
      k - key with which the specified value is associated.
      v - 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.
      See Also:
      Map.replace(Object, Object)
    • computeIfAbsent

      public short computeIfAbsent​(short k, IntUnaryOperator 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.

      Note that contrarily to the default computeIfAbsent(), it is not possible to not add a value for a given key, since the mappingFunction cannot return null. If such a behavior is needed, please use the corresponding nullable version.

      Specified by:
      computeIfAbsent in interface Short2ShortMap
      Parameters:
      k - 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.
      See Also:
      Map.computeIfAbsent(Object, java.util.function.Function)
    • computeIfAbsentNullable

      public short computeIfAbsentNullable​(short k, IntFunction<? extends Short> 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 it is null.

      Note that this version of computeIfAbsent() should be used only if you plan to return null in the mapping function.

      Specified by:
      computeIfAbsentNullable in interface Short2ShortMap
      Parameters:
      k - 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, or the default return value if the computed value is null.
      See Also:
      Map.computeIfAbsent(Object, java.util.function.Function)
    • computeIfPresent

      public short computeIfPresent​(short k, BiFunction<? super Short,​? super Short,​? extends Short> 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 Short2ShortMap
      Parameters:
      k - 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.
      See Also:
      Map.computeIfPresent(Object, java.util.function.BiFunction)
    • compute

      public short compute​(short k, BiFunction<? super Short,​? super Short,​? extends Short> 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 Short2ShortMap
      Parameters:
      k - 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.
      See Also:
      Map.compute(Object, java.util.function.BiFunction)
    • merge

      public short merge​(short k, short v, BiFunction<? super Short,​? super Short,​? extends Short> 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 Short2ShortMap
      Parameters:
      k - key with which the resulting value is to be associated.
      v - 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.
      See Also:
      Map.merge(Object, Object, java.util.function.BiFunction)
    • clear

      public void clear()
      Description copied from interface: Short2ShortMap
      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<Short,​Short>
      Specified by:
      clear in interface Map<Short,​Short>
      Specified by:
      clear in interface Short2ShortMap
      See Also:
      Map.clear()
    • size

      public int size()
      Description copied from interface: Short2ShortMap
      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<Short,​Short>
      Specified by:
      size in interface Map<Short,​Short>
      Specified by:
      size in interface Short2ShortMap
      Returns:
      the number of key-value mappings in this map.
      See Also:
      Size64
    • isEmpty

      public boolean isEmpty()
      Specified by:
      isEmpty in interface Map<Short,​Short>
      Overrides:
      isEmpty in class AbstractShort2ShortMap
    • firstShortKey

      public short firstShortKey()
      Returns the first key of this map in iteration order.
      Specified by:
      firstShortKey in interface Short2ShortSortedMap
      Returns:
      the first key in iteration order.
      See Also:
      SortedMap.firstKey()
    • lastShortKey

      public short lastShortKey()
      Returns the last key of this map in iteration order.
      Specified by:
      lastShortKey in interface Short2ShortSortedMap
      Returns:
      the last key in iteration order.
      See Also:
      SortedMap.lastKey()
    • tailMap

      public Short2ShortSortedMap tailMap​(short from)
      Returns a view of the portion of this sorted map whose keys are greater than or equal to fromKey.

      Note that this specification strengthens the one given in SortedMap.tailMap(Object).

      This implementation just throws an UnsupportedOperationException.

      Specified by:
      tailMap in interface Short2ShortSortedMap
      See Also:
      SortedMap.tailMap(Object)
    • headMap

      public Short2ShortSortedMap headMap​(short to)
      Returns a view of the portion of this sorted map whose keys are strictly less than toKey.

      Note that this specification strengthens the one given in SortedMap.headMap(Object).

      This implementation just throws an UnsupportedOperationException.

      Specified by:
      headMap in interface Short2ShortSortedMap
      See Also:
      SortedMap.headMap(Object)
    • subMap

      public Short2ShortSortedMap subMap​(short from, short to)
      Returns a view of the portion of this sorted map whose keys range from fromKey, inclusive, to toKey, exclusive.

      Note that this specification strengthens the one given in SortedMap.subMap(Object,Object).

      This implementation just throws an UnsupportedOperationException.

      Specified by:
      subMap in interface Short2ShortSortedMap
      See Also:
      SortedMap.subMap(Object,Object)
    • comparator

      public ShortComparator comparator()
      Returns the comparator associated with this sorted set, or null if it uses its keys' natural ordering.

      Note that this specification strengthens the one given in SortedMap.comparator().

      This implementation just returns null.

      Specified by:
      comparator in interface Short2ShortSortedMap
      Specified by:
      comparator in interface SortedMap<Short,​Short>
      See Also:
      SortedMap.comparator()
    • short2ShortEntrySet

      public Short2ShortSortedMap.FastSortedEntrySet short2ShortEntrySet()
      Description copied from interface: Short2ShortSortedMap
      Returns a type-specific sorted-set view of the mappings contained in this map.

      Note that this specification strengthens the one given in the corresponding type-specific unsorted map.

      Specified by:
      short2ShortEntrySet in interface Short2ShortMap
      Specified by:
      short2ShortEntrySet in interface Short2ShortSortedMap
      Returns:
      a type-specific sorted-set view of the mappings contained in this map.
      See Also:
      Short2ShortSortedMap.entrySet()
    • keySet

      public ShortSortedSet keySet()
      Description copied from class: AbstractShort2ShortSortedMap
      Returns a type-specific-set view of the keys of this map.

      The view is backed by the set returned by Map.entrySet(). Note that no attempt is made at caching the result of this method, as this would require adding some attributes that lightweight implementations would not need. Subclasses may easily override this policy by calling this method and caching the result, but implementors are encouraged to write more efficient ad-hoc implementations.

      The view is backed by the sorted set returned by Map.entrySet(). Note that no attempt is made at caching the result of this method, as this would require adding some attributes that lightweight implementations would not need. Subclasses may easily override this policy by calling this method and caching the result, but implementors are encouraged to write more efficient ad-hoc implementations.

      Specified by:
      keySet in interface Map<Short,​Short>
      Specified by:
      keySet in interface Short2ShortMap
      Specified by:
      keySet in interface Short2ShortSortedMap
      Specified by:
      keySet in interface SortedMap<Short,​Short>
      Overrides:
      keySet in class AbstractShort2ShortSortedMap
      Returns:
      a sorted set view of the keys of this map; it may be safely cast to a type-specific interface.
      See Also:
      Map.keySet()
    • values

      public ShortCollection values()
      Description copied from class: AbstractShort2ShortSortedMap
      Returns a type-specific-set view of the values of this map.

      The view is backed by the set returned by Map.entrySet(). Note that no attempt is made at caching the result of this method, as this would require adding some attributes that lightweight implementations would not need. Subclasses may easily override this policy by calling this method and caching the result, but implementors are encouraged to write more efficient ad-hoc implementations.

      The view is backed by the sorted set returned by Map.entrySet(). Note that no attempt is made at caching the result of this method, as this would require adding some attributes that lightweight implementations would not need. Subclasses may easily override this policy by calling this method and caching the result, but implementors are encouraged to write more efficient ad-hoc implementations.

      Specified by:
      values in interface Map<Short,​Short>
      Specified by:
      values in interface Short2ShortMap
      Specified by:
      values in interface Short2ShortSortedMap
      Specified by:
      values in interface SortedMap<Short,​Short>
      Overrides:
      values in class AbstractShort2ShortSortedMap
      Returns:
      a type-specific collection view of the values contained in this map.
      See Also:
      Map.values()
    • trim

      public boolean trim()
      Rehashes the map, making the table as small as possible.

      This method rehashes the table to the smallest size satisfying the load factor. It can be used when the set will not be changed anymore, so to optimize access speed and size.

      If the table size is already the minimum possible, this method does nothing.

      Returns:
      true if there was enough memory to trim the map.
      See Also:
      trim(int)
    • trim

      public boolean trim​(int n)
      Rehashes this map if the table is too large.

      Let N be the smallest table size that can hold max(n,size()) entries, still satisfying the load factor. If the current table size is smaller than or equal to N, this method does nothing. Otherwise, it rehashes this map in a table of size N.

      This method is useful when reusing maps. Clearing a map leaves the table size untouched. If you are reusing a map many times, you can call this method with a typical size to avoid keeping around a very large table just because of a few large transient maps.

      Parameters:
      n - the threshold for the trimming.
      Returns:
      true if there was enough memory to trim the map.
      See Also:
      trim()
    • clone

      Returns a deep copy of this map.

      This method performs a deep copy of this hash map; the data stored in the map, however, is not cloned. Note that this makes a difference only for object keys.

      Returns:
      a deep copy of this map.
    • hashCode

      public int hashCode()
      Returns a hash code for this map. This method overrides the generic method provided by the superclass. Since equals() is not overriden, it is important that the value returned by this method is the same value as the one returned by the overriden method.
      Specified by:
      hashCode in interface Map<Short,​Short>
      Overrides:
      hashCode in class AbstractShort2ShortMap
      Returns:
      a hash code for this map.