Class CharLinkedOpenHashSet

  • All Implemented Interfaces:
    CharBidirectionalIterable, CharCollection, CharIterable, CharSet, CharSortedSet, Hash, java.io.Serializable, java.lang.Cloneable, java.lang.Iterable<java.lang.Character>, java.util.Collection<java.lang.Character>, java.util.Set<java.lang.Character>, java.util.SortedSet<java.lang.Character>

    public class CharLinkedOpenHashSet
    extends AbstractCharSortedSet
    implements java.io.Serializable, java.lang.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:
    Hash, HashCommon, Serialized Form
    • Constructor Detail

      • CharLinkedOpenHashSet

        public CharLinkedOpenHashSet​(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.
      • CharLinkedOpenHashSet

        public CharLinkedOpenHashSet​(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.
      • CharLinkedOpenHashSet

        public CharLinkedOpenHashSet​(java.util.Collection<? extends java.lang.Character> 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.
      • CharLinkedOpenHashSet

        public CharLinkedOpenHashSet​(java.util.Collection<? extends java.lang.Character> 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.
      • CharLinkedOpenHashSet

        public CharLinkedOpenHashSet​(CharCollection 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.
      • CharLinkedOpenHashSet

        public CharLinkedOpenHashSet​(CharCollection 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.
      • CharLinkedOpenHashSet

        public CharLinkedOpenHashSet​(CharIterator 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.
      • CharLinkedOpenHashSet

        public CharLinkedOpenHashSet​(CharIterator 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.
      • CharLinkedOpenHashSet

        public CharLinkedOpenHashSet​(java.util.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.
      • CharLinkedOpenHashSet

        public CharLinkedOpenHashSet​(java.util.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.
      • CharLinkedOpenHashSet

        public CharLinkedOpenHashSet​(char[] 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.
      • CharLinkedOpenHashSet

        public CharLinkedOpenHashSet​(char[] 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.
      • CharLinkedOpenHashSet

        public CharLinkedOpenHashSet​(char[] 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.
      • CharLinkedOpenHashSet

        public CharLinkedOpenHashSet​(char[] 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 Detail

      • addAll

        public boolean addAll​(CharCollection c)
        Description copied from interface: CharCollection
        Adds all elements of the given type-specific collection to this collection.
        Specified by:
        addAll in interface CharCollection
        Overrides:
        addAll in class AbstractCharCollection
        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​(java.util.Collection<? extends java.lang.Character> c)
        Specified by:
        addAll in interface java.util.Collection<java.lang.Character>
        Specified by:
        addAll in interface java.util.Set<java.lang.Character>
        Overrides:
        addAll in class java.util.AbstractCollection<java.lang.Character>
      • add

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

        This implementation always throws an UnsupportedOperationException.

        Specified by:
        add in interface CharCollection
        Overrides:
        add in class AbstractCharCollection
        See Also:
        Collection.add(Object)
      • remove

        public boolean remove​(char k)
        Description copied from class: AbstractCharSet
        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 CharSet
        Overrides:
        remove in class AbstractCharSet
        See Also:
        Collection.remove(Object)
      • contains

        public boolean contains​(char k)
        Description copied from class: AbstractCharCollection
        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 CharCollection
        Overrides:
        contains in class AbstractCharCollection
        See Also:
        Collection.contains(Object)
      • removeFirstChar

        public char removeFirstChar()
        Removes the first key in iteration order.
        Returns:
        the first key.
        Throws:
        java.util.NoSuchElementException - is this set is empty.
      • removeLastChar

        public char removeLastChar()
        Removes the the last key in iteration order.
        Returns:
        the last key.
        Throws:
        java.util.NoSuchElementException - is this set is empty.
      • addAndMoveToFirst

        public boolean addAndMoveToFirst​(char k)
        Adds a key to the set; if the key is already present, it is moved to the first position of the iteration order.
        Parameters:
        k - the key.
        Returns:
        true if the key was not present.
      • addAndMoveToLast

        public boolean addAndMoveToLast​(char k)
        Adds a key to the set; if the key is already present, it is moved to the last position of the iteration order.
        Parameters:
        k - the key.
        Returns:
        true if the key was not present.
      • clear

        public void clear()
        Specified by:
        clear in interface java.util.Collection<java.lang.Character>
        Specified by:
        clear in interface java.util.Set<java.lang.Character>
        Overrides:
        clear in class java.util.AbstractCollection<java.lang.Character>
      • size

        public int size()
        Specified by:
        size in interface java.util.Collection<java.lang.Character>
        Specified by:
        size in interface java.util.Set<java.lang.Character>
        Specified by:
        size in class java.util.AbstractCollection<java.lang.Character>
      • isEmpty

        public boolean isEmpty()
        Specified by:
        isEmpty in interface java.util.Collection<java.lang.Character>
        Specified by:
        isEmpty in interface java.util.Set<java.lang.Character>
        Overrides:
        isEmpty in class java.util.AbstractCollection<java.lang.Character>
      • firstChar

        public char firstChar()
        Returns the first element of this set in iteration order.
        Specified by:
        firstChar in interface CharSortedSet
        Returns:
        the first element in iteration order.
        See Also:
        SortedSet.first()
      • lastChar

        public char lastChar()
        Returns the last element of this set in iteration order.
        Specified by:
        lastChar in interface CharSortedSet
        Returns:
        the last element in iteration order.
        See Also:
        SortedSet.last()
      • tailSet

        public CharSortedSet tailSet​(char from)
        Returns a view of the portion of this sorted set whose elements are greater than or equal to fromElement.

        Note that this specification strengthens the one given in SortedSet.headSet(Object).

        This implementation just throws an UnsupportedOperationException.

        Specified by:
        tailSet in interface CharSortedSet
        See Also:
        SortedSet.tailSet(Object)
      • headSet

        public CharSortedSet headSet​(char to)
        Returns a view of the portion of this sorted set whose elements are strictly less than toElement.

        Note that this specification strengthens the one given in SortedSet.headSet(Object).

        This implementation just throws an UnsupportedOperationException.

        Specified by:
        headSet in interface CharSortedSet
        See Also:
        SortedSet.headSet(Object)
      • subSet

        public CharSortedSet subSet​(char from,
                                    char to)
        Returns a view of the portion of this sorted set whose elements range from fromElement, inclusive, to toElement, exclusive.

        Note that this specification strengthens the one given in SortedSet.subSet(Object,Object).

        This implementation just throws an UnsupportedOperationException.

        Specified by:
        subSet in interface CharSortedSet
        See Also:
        SortedSet.subSet(Object,Object)
      • comparator

        public CharComparator comparator()

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

        This implementation just returns null.

        Specified by:
        comparator in interface CharSortedSet
        Specified by:
        comparator in interface java.util.SortedSet<java.lang.Character>
      • iterator

        public CharListIterator iterator​(char from)
        Returns a type-specific list iterator on the elements in this set, starting from a given element of the set. Please see the class documentation for implementation details.
        Specified by:
        iterator in interface CharSortedSet
        Parameters:
        from - an element to start from.
        Returns:
        a type-specific list iterator starting at the given element.
        Throws:
        java.lang.IllegalArgumentException - if from does not belong to the set.
      • iterator

        public CharListIterator iterator()
        Returns a type-specific list iterator on the elements in this set, starting from the first element. Please see the class documentation for implementation details.
        Specified by:
        iterator in interface CharBidirectionalIterable
        Specified by:
        iterator in interface CharCollection
        Specified by:
        iterator in interface CharIterable
        Specified by:
        iterator in interface CharSet
        Specified by:
        iterator in interface CharSortedSet
        Specified by:
        iterator in interface java.util.Collection<java.lang.Character>
        Specified by:
        iterator in interface java.lang.Iterable<java.lang.Character>
        Specified by:
        iterator in interface java.util.Set<java.lang.Character>
        Specified by:
        iterator in class AbstractCharSortedSet
        Returns:
        a type-specific list iterator starting at the first element.
        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 CharLinkedOpenHashSet 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 java.util.Collection<java.lang.Character>
        Specified by:
        hashCode in interface java.util.Set<java.lang.Character>
        Overrides:
        hashCode in class AbstractCharSet
        Returns:
        a hash code for this set.