Class ByteOpenCustomHashSet

java.lang.Object
java.util.AbstractCollection<Byte>
it.unimi.dsi.fastutil.bytes.AbstractByteCollection
it.unimi.dsi.fastutil.bytes.AbstractByteSet
it.unimi.dsi.fastutil.bytes.ByteOpenCustomHashSet
All Implemented Interfaces:
ByteCollection, ByteIterable, ByteSet, Hash, Serializable, Cloneable, Iterable<Byte>, Collection<Byte>, Set<Byte>
public class ByteOpenCustomHashSet extends AbstractByteSet implements Serializable, Cloneable, Hash
A type-specific hash set with a fast, small-footprint implementation whose hashing strategy is specified at creation time.

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:

  • Constructor Details

    • ByteOpenCustomHashSet

      public ByteOpenCustomHashSet(int expected, float f, ByteHash.Strategy strategy)
      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.
      strategy - the strategy.

    • ByteOpenCustomHashSet

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

    • ByteOpenCustomHashSet

      public ByteOpenCustomHashSet(ByteHash.Strategy strategy)
      Creates a new hash set with initial expected Hash.DEFAULT_INITIAL_SIZE elements and Hash.DEFAULT_LOAD_FACTOR as load factor.
      Parameters:
      strategy - the strategy.

    • ByteOpenCustomHashSet

      public ByteOpenCustomHashSet(Collection<? extends Byte> c, float f, ByteHash.Strategy strategy)
      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.
      strategy - the strategy.

    • ByteOpenCustomHashSet

      public ByteOpenCustomHashSet(Collection<? extends Byte> c, ByteHash.Strategy strategy)
      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.
      strategy - the strategy.

    • ByteOpenCustomHashSet

      public ByteOpenCustomHashSet(ByteCollection c, float f, ByteHash.Strategy strategy)
      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.
      strategy - the strategy.

    • ByteOpenCustomHashSet

      public ByteOpenCustomHashSet(ByteCollection c, ByteHash.Strategy strategy)
      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.
      strategy - the strategy.

    • ByteOpenCustomHashSet

      public ByteOpenCustomHashSet(ByteIterator i, float f, ByteHash.Strategy strategy)
      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.
      strategy - the strategy.

    • ByteOpenCustomHashSet

      public ByteOpenCustomHashSet(ByteIterator i, ByteHash.Strategy strategy)
      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.
      strategy - the strategy.

    • ByteOpenCustomHashSet

      public ByteOpenCustomHashSet(Iterator<?> i, float f, ByteHash.Strategy strategy)
      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.
      strategy - the strategy.

    • ByteOpenCustomHashSet

      public ByteOpenCustomHashSet(Iterator<?> i, ByteHash.Strategy strategy)
      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.
      strategy - the strategy.

    • ByteOpenCustomHashSet

      public ByteOpenCustomHashSet(byte[] a, int offset, int length, float f, ByteHash.Strategy strategy)
      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.
      strategy - the strategy.

    • ByteOpenCustomHashSet

      public ByteOpenCustomHashSet(byte[] a, int offset, int length, ByteHash.Strategy strategy)
      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.
      strategy - the strategy.

    • ByteOpenCustomHashSet

      public ByteOpenCustomHashSet(byte[] a, float f, ByteHash.Strategy strategy)
      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.
      strategy - the strategy.

    • ByteOpenCustomHashSet

      public ByteOpenCustomHashSet(byte[] a, ByteHash.Strategy strategy)
      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.
      strategy - the strategy.

  • Method Details

    • strategy

      public ByteHash.Strategy strategy()
      Returns the hashing strategy.
      Returns:
      the hashing strategy of this custom hash set.

    • ensureCapacity

      public void ensureCapacity(int capacity)
      Ensures that this set can hold a certain number of elements without rehashing.
      Parameters:
      capacity - a number of elements; there will be no rehashing unless the set size exceeds this number.

    • addAll

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

    • addAll

      public boolean addAll(Collection<? extends Byte> c)
      Description copied from class: AbstractByteCollection
      Specified by:
      addAll in interface Collection<Byte>
      Specified by:
      addAll in interface Set<Byte>
      Overrides:
      addAll in class AbstractByteCollection

    • add

      public boolean add(byte k)
      Description copied from class: AbstractByteCollection
      Ensures that this collection contains the specified element (optional operation).
      Specified by:
      add in interface ByteCollection
      Overrides:
      add in class AbstractByteCollection
      See Also:

    • remove

      public boolean remove(byte k)
      Description copied from class: AbstractByteSet
      Removes an element from this set. Delegates to the type-specific rem() method implemented by type-specific abstract Collection superclass.
      Specified by:
      remove in interface ByteSet
      Overrides:
      remove in class AbstractByteSet
      See Also:

    • contains

      public boolean contains(byte k)
      Description copied from class: AbstractByteCollection
      Returns true if this collection contains the specified element.
      Specified by:
      contains in interface ByteCollection
      Overrides:
      contains in class AbstractByteCollection
      See Also:

    • clear

      public void clear()
      Removes all elements from this set.

      To increase object reuse, this method does not change the table size. If you want to reduce the table size, you must use trim().

      Specified by:
      clear in interface Collection<Byte>
      Specified by:
      clear in interface Set<Byte>
      Overrides:
      clear in class AbstractCollection<Byte>

    • size

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

    • isEmpty

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

    • iterator

      public ByteIterator iterator()
      Description copied from interface: ByteCollection
      Returns a type-specific iterator on the elements of this collection.
      Specified by:
      iterator in interface ByteCollection
      Specified by:
      iterator in interface ByteIterable
      Specified by:
      iterator in interface ByteSet
      Specified by:
      iterator in interface Collection<Byte>
      Specified by:
      iterator in interface Iterable<Byte>
      Specified by:
      iterator in interface Set<Byte>
      Specified by:
      iterator in class AbstractByteSet
      Returns:
      a type-specific iterator on the elements of this collection.
      See Also:

    • spliterator

      public ByteSpliterator spliterator()
      Description copied from interface: ByteCollection
      Returns a type-specific spliterator on the elements of this collection.

      See Collection.spliterator() for more documentation on the requirements of the returned spliterator.

      Specified by:
      spliterator in interface ByteCollection
      Specified by:
      spliterator in interface ByteIterable
      Specified by:
      spliterator in interface ByteSet
      Specified by:
      spliterator in interface Collection<Byte>
      Specified by:
      spliterator in interface Iterable<Byte>
      Specified by:
      spliterator in interface Set<Byte>
      Returns:
      a type-specific spliterator on the elements of this collection.

    • forEach

      public void forEach(ByteConsumer action)
      Description copied from interface: ByteIterable
      Performs the given action for each element of this type-specific Iterable until all elements have been processed or the action throws an exception.
      Specified by:
      forEach in interface ByteIterable
      Parameters:
      action - the action to be performed for each element.
      See Also:

    • 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

      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:

    • clone

      public ByteOpenCustomHashSet 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<Byte>
      Specified by:
      hashCode in interface Set<Byte>
      Overrides:
      hashCode in class AbstractByteSet
      Returns:
      a hash code for this set.