Package it.unimi.dsi.fastutil.shorts

Class ShortOpenHashSet

java.lang.Object
java.util.AbstractCollection<Short>
it.unimi.dsi.fastutil.shorts.AbstractShortCollection
it.unimi.dsi.fastutil.shorts.AbstractShortSet
it.unimi.dsi.fastutil.shorts.ShortOpenHashSet
All Implemented Interfaces:
Hash, ShortCollection, ShortIterable, ShortSet, Serializable, Cloneable, Iterable<Short>, Collection<Short>, Set<Short>
public class ShortOpenHashSet
extends AbstractShortSet
implements Serializable, Cloneable, Hash
A type-specific 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.

See Also:
Hash, HashCommon, Serialized Form

  • Constructor Details

    • ShortOpenHashSet

      public ShortOpenHashSet​(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.

    • ShortOpenHashSet

      public ShortOpenHashSet​(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.

    • ShortOpenHashSet

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

    • ShortOpenHashSet

      public ShortOpenHashSet​(Collection<? extends Short> 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.

    • ShortOpenHashSet

      public ShortOpenHashSet​(Collection<? extends Short> 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.

    • ShortOpenHashSet

      public ShortOpenHashSet​(ShortCollection 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.

    • ShortOpenHashSet

      public ShortOpenHashSet​(ShortCollection 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.

    • ShortOpenHashSet

      public ShortOpenHashSet​(ShortIterator 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.

    • ShortOpenHashSet

      public ShortOpenHashSet​(ShortIterator 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.

    • ShortOpenHashSet

      public ShortOpenHashSet​(Iterator<?> i, float f)
      Creates a new hash set using elements provided by an iterator.
      Parameters:
      i - an iterator whose elements will fill the set.
      f - the load factor.

    • ShortOpenHashSet

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

    • ShortOpenHashSet

      public ShortOpenHashSet​(short[] 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.

    • ShortOpenHashSet

      public ShortOpenHashSet​(short[] 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.

    • ShortOpenHashSet

      public ShortOpenHashSet​(short[] 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.

    • ShortOpenHashSet

      public ShortOpenHashSet​(short[] 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

    • addAll

      public boolean addAll​(ShortCollection c)
      Description copied from interface: ShortCollection
      Adds all elements of the given type-specific collection to this collection.
      Specified by:
      addAll in interface ShortCollection
      Overrides:
      addAll in class AbstractShortCollection
      Parameters:
      c - a type-specific collection.
      Returns:
      true if this collection changed as a result of the call.
      See Also:
      Collection.addAll(Collection)

    • addAll

      public boolean addAll​(Collection<? extends Short> c)
      Specified by:
      addAll in interface Collection<Short>
      Specified by:
      addAll in interface Set<Short>
      Overrides:
      addAll in class AbstractCollection<Short>

    • add

      public boolean add​(short k)
      Description copied from class: AbstractShortCollection
      Ensures that this collection contains the specified element (optional operation).

      This implementation always throws an UnsupportedOperationException.

      Specified by:
      add in interface ShortCollection
      Overrides:
      add in class AbstractShortCollection
      See Also:
      Collection.add(Object)

    • remove

      public boolean remove​(short k)
      Description copied from class: AbstractShortSet
      Removes an element from this set.

      Note that the corresponding method of a type-specific collection is rem(). This unfortunate situation is caused by the clash with the similarly named index-based method in the List interface. Delegates to the type-specific rem() method implemented by type-specific abstract Collection superclass.

      Specified by:
      remove in interface ShortSet
      Overrides:
      remove in class AbstractShortSet
      See Also:
      Collection.remove(Object)

    • contains

      public boolean contains​(short k)
      Description copied from class: AbstractShortCollection
      Returns true if this collection contains the specified element.

      This implementation iterates over the elements in the collection, looking for the specified element.

      Specified by:
      contains in interface ShortCollection
      Overrides:
      contains in class AbstractShortCollection
      See Also:
      Collection.contains(Object)

    • clear

      public void clear()
      Specified by:
      clear in interface Collection<Short>
      Specified by:
      clear in interface Set<Short>
      Overrides:
      clear in class AbstractCollection<Short>

    • size

      public int size()
      Specified by:
      size in interface Collection<Short>
      Specified by:
      size in interface Set<Short>
      Specified by:
      size in class AbstractCollection<Short>

    • isEmpty

      public boolean isEmpty()
      Specified by:
      isEmpty in interface Collection<Short>
      Specified by:
      isEmpty in interface Set<Short>
      Overrides:
      isEmpty in class AbstractCollection<Short>

    • iterator

      public ShortIterator iterator()
      Description copied from interface: ShortCollection
      Returns a type-specific iterator on the elements of this collection.

      Note that this specification strengthens the one given in Iterable.iterator(), which was already strengthened in the corresponding type-specific class, but was weakened by the fact that this interface extends Collection.

      Specified by:
      iterator in interface Collection<Short>
      Specified by:
      iterator in interface Iterable<Short>
      Specified by:
      iterator in interface Set<Short>
      Specified by:
      iterator in interface ShortCollection
      Specified by:
      iterator in interface ShortIterable
      Specified by:
      iterator in interface ShortSet
      Specified by:
      iterator in class AbstractShortSet
      Returns:
      a type-specific iterator on the elements of this collection.
      See Also:
      Iterable.iterator()

    • trim

      public boolean trim()
      Rehashes this set, 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 set.
      See Also:
      trim(int)

    • trim

      public boolean trim​(int n)
      Rehashes this set 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 set in a table of size N.

      This method is useful when reusing sets. Clearing a set leaves the table size untouched. If you are reusing a set 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 sets.

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

    • clone

      public ShortOpenHashSet clone()
      Returns a deep copy of this set.

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

      Returns:
      a deep copy of this set.

    • hashCode

      public int hashCode()
      Returns a hash code for this set. 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 Collection<Short>
      Specified by:
      hashCode in interface Set<Short>
      Overrides:
      hashCode in class AbstractShortSet
      Returns:
      a hash code for this set.