Package it.unimi.dsi.fastutil.objects

Class ReferenceLinkedOpenHashSet<K>

java.lang.Object
java.util.AbstractCollection<K>
it.unimi.dsi.fastutil.objects.AbstractReferenceCollection<K>
it.unimi.dsi.fastutil.objects.AbstractReferenceSet<K>
it.unimi.dsi.fastutil.objects.AbstractReferenceSortedSet<K>
it.unimi.dsi.fastutil.objects.ReferenceLinkedOpenHashSet<K>
All Implemented Interfaces:
Hash, ObjectBidirectionalIterable<K>, ObjectIterable<K>, ReferenceCollection<K>, ReferenceSet<K>, ReferenceSortedSet<K>, Serializable, Cloneable, Iterable<K>, Collection<K>, SequencedCollection<K>, SequencedSet<K>, Set<K>, SortedSet<K>
public class ReferenceLinkedOpenHashSet<K> extends AbstractReferenceSortedSet<K> implements Serializable, Cloneable, Hash
A type-specific linked hash set with with a fast, small-footprint implementation.

Instances of this class use a hash table to represent a set. 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 sets 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 set will enumerate elements in the same order in which they have been added to the set (addition of elements already present in the set 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 set, so to allow easy access of the iteration order: for instance, you can get the first element in iteration order with first() without having to create an iterator; however, this class partially violates the SortedSet contract because all subset methods throw an exception and comparator() returns always null.

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

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

See Also:

  • Constructor Details

    • ReferenceLinkedOpenHashSet

      public ReferenceLinkedOpenHashSet(int expected, float f)
      Creates a new hash set.

      The actual table size will be the least power of two greater than expected/f.

      Parameters:
      expected - the expected number of elements in the hash set.
      f - the load factor.

    • ReferenceLinkedOpenHashSet

      public ReferenceLinkedOpenHashSet(int expected)
      Creates a new hash set with Hash.DEFAULT_LOAD_FACTOR as load factor.
      Parameters:
      expected - the expected number of elements in the hash set.

    • ReferenceLinkedOpenHashSet

      public ReferenceLinkedOpenHashSet()
      Creates a new hash set with initial expected Hash.DEFAULT_INITIAL_SIZE elements and Hash.DEFAULT_LOAD_FACTOR as load factor.

    • ReferenceLinkedOpenHashSet

      public ReferenceLinkedOpenHashSet(Collection<? extends K> c, float f)
      Creates a new hash set copying a given collection.
      Parameters:
      c - a Collection to be copied into the new hash set.
      f - the load factor.

    • ReferenceLinkedOpenHashSet

      public ReferenceLinkedOpenHashSet(Collection<? extends K> c)
      Creates a new hash set with Hash.DEFAULT_LOAD_FACTOR as load factor copying a given collection.
      Parameters:
      c - a Collection to be copied into the new hash set.

    • ReferenceLinkedOpenHashSet

      public ReferenceLinkedOpenHashSet(ReferenceCollection<? extends K> c, float f)
      Creates a new hash set copying a given type-specific collection.
      Parameters:
      c - a type-specific collection to be copied into the new hash set.
      f - the load factor.

    • ReferenceLinkedOpenHashSet

      public ReferenceLinkedOpenHashSet(ReferenceCollection<? extends K> c)
      Creates a new hash set with Hash.DEFAULT_LOAD_FACTOR as load factor copying a given type-specific collection.
      Parameters:
      c - a type-specific collection to be copied into the new hash set.

    • ReferenceLinkedOpenHashSet

      public ReferenceLinkedOpenHashSet(Iterator<? extends K> i, float f)
      Creates a new hash set using elements provided by a type-specific iterator.
      Parameters:
      i - a type-specific iterator whose elements will fill the set.
      f - the load factor.

    • ReferenceLinkedOpenHashSet

      public ReferenceLinkedOpenHashSet(Iterator<? extends K> i)
      Creates a new hash set with Hash.DEFAULT_LOAD_FACTOR as load factor using elements provided by a type-specific iterator.
      Parameters:
      i - a type-specific iterator whose elements will fill the set.

    • ReferenceLinkedOpenHashSet

      public ReferenceLinkedOpenHashSet(K[] a, int offset, int length, float f)
      Creates a new hash set and fills it with the elements of a given array.
      Parameters:
      a - an array whose elements will be used to fill the set.
      offset - the first element to use.
      length - the number of elements to use.
      f - the load factor.

    • ReferenceLinkedOpenHashSet

      public ReferenceLinkedOpenHashSet(K[] a, int offset, int length)
      Creates a new hash set with Hash.DEFAULT_LOAD_FACTOR as load factor and fills it with the elements of a given array.
      Parameters:
      a - an array whose elements will be used to fill the set.
      offset - the first element to use.
      length - the number of elements to use.

    • ReferenceLinkedOpenHashSet

      public ReferenceLinkedOpenHashSet(K[] a, float f)
      Creates a new hash set copying the elements of an array.
      Parameters:
      a - an array to be copied into the new hash set.
      f - the load factor.

    • ReferenceLinkedOpenHashSet

      public ReferenceLinkedOpenHashSet(K[] a)
      Creates a new hash set with Hash.DEFAULT_LOAD_FACTOR as load factor copying the elements of an array.
      Parameters:
      a - an array to be copied into the new hash set.

  • Method Details