Class Reference2LongLinkedOpenHashMap<K>

All Implemented Interfaces:
Function<K,​Long>, Hash, Reference2LongFunction<K>, Reference2LongMap<K>, Reference2LongSortedMap<K>, Serializable, Cloneable, Function<K,​Long>, ToLongFunction<K>, Map<K,​Long>, SortedMap<K,​Long>

public class Reference2LongLinkedOpenHashMap<K>
extends AbstractReference2LongSortedMap<K>
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 K,​? extends Long> m)
      Description copied from class: AbstractReference2LongMap
      Specified by:
      putAll in interface Map<K,​Long>
      Overrides:
      putAll in class AbstractReference2LongMap<K>
    • put

      public long put​(K k, long v)
      Description copied from interface: Reference2LongFunction
      Adds a pair to the map (optional operation).
      Specified by:
      put in interface Reference2LongFunction<K>
      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 long addTo​(K k, long 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.
    • removeLong

      public long removeLong​(Object k)
      Description copied from interface: Reference2LongFunction
      Removes the mapping with the given key (optional operation).
      Specified by:
      removeLong in interface Reference2LongFunction<K>
      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)
    • removeFirstLong

      public long removeFirstLong()
      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.
    • removeLastLong

      public long removeLastLong()
      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 long getAndMoveToFirst​(K 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 long getAndMoveToLast​(K 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 long putAndMoveToFirst​(K k, long 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 long putAndMoveToLast​(K k, long 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.
    • getLong

      public long getLong​(Object k)
      Description copied from interface: Reference2LongFunction
      Returns the value to which the given key is mapped.
      Specified by:
      getLong in interface Reference2LongFunction<K>
      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​(Object k)
      Description copied from interface: Reference2LongMap
      Returns true if this function contains a mapping for the specified key.
      Specified by:
      containsKey in interface Function<K,​Long>
      Specified by:
      containsKey in interface Map<K,​Long>
      Specified by:
      containsKey in interface Reference2LongMap<K>
      Overrides:
      containsKey in class AbstractReference2LongMap<K>
      Parameters:
      k - the key.
      Returns:
      true if this function associates a value to key.
      See Also:
      Map.containsKey(Object)
    • containsValue

      public boolean containsValue​(long v)
      Description copied from interface: Reference2LongMap
      Returns true if this map maps one or more keys to the specified value.
      Specified by:
      containsValue in interface Reference2LongMap<K>
      Overrides:
      containsValue in class AbstractReference2LongMap<K>
      See Also:
      Map.containsValue(Object)
    • getOrDefault

      public long getOrDefault​(Object k, long 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 Reference2LongMap<K>
      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 long putIfAbsent​(K k, long 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 Reference2LongMap<K>
      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​(Object k, long v)
      Removes the entry for the specified key only if it is currently mapped to the specified value.
      Specified by:
      remove in interface Reference2LongMap<K>
      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​(K k, long oldValue, long v)
      Replaces the entry for the specified key only if currently mapped to the specified value.
      Specified by:
      replace in interface Reference2LongMap<K>
      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 long replace​(K k, long v)
      Replaces the entry for the specified key only if it is currently mapped to some value.
      Specified by:
      replace in interface Reference2LongMap<K>
      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)
    • computeLongIfAbsent

      public long computeLongIfAbsent​(K k, ToLongFunction<? super K> 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:
      computeLongIfAbsent in interface Reference2LongMap<K>
      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)
    • computeLongIfPresent

      public long computeLongIfPresent​(K k, BiFunction<? super K,​? super Long,​? extends Long> 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:
      computeLongIfPresent in interface Reference2LongMap<K>
      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)
    • computeLong

      public long computeLong​(K k, BiFunction<? super K,​? super Long,​? extends Long> 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:
      computeLong in interface Reference2LongMap<K>
      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)
    • mergeLong

      public long mergeLong​(K k, long v, BiFunction<? super Long,​? super Long,​? extends Long> 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:
      mergeLong in interface Reference2LongMap<K>
      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: Reference2LongMap
      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,​Long>
      Specified by:
      clear in interface Map<K,​Long>
      Specified by:
      clear in interface Reference2LongMap<K>
      See Also:
      Map.clear()
    • size

      public int size()
      Description copied from interface: Reference2LongMap
      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,​Long>
      Specified by:
      size in interface Map<K,​Long>
      Specified by:
      size in interface Reference2LongMap<K>
      Returns:
      the number of key-value mappings in this map.
      See Also:
      Size64
    • isEmpty

      public boolean isEmpty()
      Specified by:
      isEmpty in interface Map<K,​Long>
      Overrides:
      isEmpty in class AbstractReference2LongMap<K>
    • firstKey

      public K firstKey()
      Returns the first key of this map in iteration order.
      Specified by:
      firstKey in interface SortedMap<K,​Long>
      Returns:
      the first key in iteration order.
    • lastKey

      public K lastKey()
      Returns the last key of this map in iteration order.
      Specified by:
      lastKey in interface SortedMap<K,​Long>
      Returns:
      the last key in iteration order.
    • tailMap

      public Reference2LongSortedMap<K> tailMap​(K 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 Reference2LongSortedMap<K>
      Specified by:
      tailMap in interface SortedMap<K,​Long>
      See Also:
      SortedMap.tailMap(Object)
    • headMap

      public Reference2LongSortedMap<K> headMap​(K 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 Reference2LongSortedMap<K>
      Specified by:
      headMap in interface SortedMap<K,​Long>
      See Also:
      SortedMap.headMap(Object)
    • subMap

      public Reference2LongSortedMap<K> subMap​(K from, K 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 Reference2LongSortedMap<K>
      Specified by:
      subMap in interface SortedMap<K,​Long>
      See Also:
      SortedMap.subMap(Object,Object)
    • comparator

      public Comparator<? super K> 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 Reference2LongSortedMap<K>
      Specified by:
      comparator in interface SortedMap<K,​Long>
      See Also:
      SortedMap.comparator()
    • reference2LongEntrySet

      public Reference2LongSortedMap.FastSortedEntrySet<K> reference2LongEntrySet()
      Description copied from interface: Reference2LongSortedMap
      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:
      reference2LongEntrySet in interface Reference2LongMap<K>
      Specified by:
      reference2LongEntrySet in interface Reference2LongSortedMap<K>
      Returns:
      a type-specific sorted-set view of the mappings contained in this map.
      See Also:
      Reference2LongSortedMap.entrySet()
    • keySet

      public ReferenceSortedSet<K> keySet()
      Description copied from class: AbstractReference2LongSortedMap
      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<K,​Long>
      Specified by:
      keySet in interface Reference2LongMap<K>
      Specified by:
      keySet in interface Reference2LongSortedMap<K>
      Specified by:
      keySet in interface SortedMap<K,​Long>
      Overrides:
      keySet in class AbstractReference2LongSortedMap<K>
      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 LongCollection values()
      Description copied from class: AbstractReference2LongSortedMap
      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<K,​Long>
      Specified by:
      values in interface Reference2LongMap<K>
      Specified by:
      values in interface Reference2LongSortedMap<K>
      Specified by:
      values in interface SortedMap<K,​Long>
      Overrides:
      values in class AbstractReference2LongSortedMap<K>
      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<K,​Long>
      Overrides:
      hashCode in class AbstractReference2LongMap<K>
      Returns:
      a hash code for this map.