Class TreeSet<E>

java.lang.Object
java.util.AbstractCollection<E>
java.util.AbstractSet<E>
java.util.TreeSet<E>
All Implemented Interfaces:
Iterable<E>, Collection<E>, NavigableSet<E>, Set<E>, SortedSet<E>
public class TreeSet<E> extends AbstractSet<E> implements NavigableSet<E>
TreeSet is an implementation of SortedSet. All optional operations (adding and removing) are supported. The elements can be any objects which are comparable to each other either using their natural order or a specified Comparator.
Since:
1.2

  • Constructor Summary

    Constructors
    Constructor
    Description
    TreeSet()
    Constructs a new empty instance of TreeSet which uses natural ordering.
    TreeSet(Collection<? extends E> collection)
    Constructs a new instance of TreeSet which uses natural ordering and containing the unique elements in the specified collection.
    TreeSet(Comparator<? super E> comparator)
    Constructs a new empty instance of TreeSet which uses the specified comparator.
    TreeSet(SortedSet<E> set)
    Constructs a new instance of TreeSet containing the elements of the specified SortedSet and using the same Comparator.

  • Method Summary

    Modifier and Type
    Method
    Description
    boolean
    add(E object)
    Adds the specified object to this TreeSet.
    boolean
    addAll(Collection<? extends E> collection)
    Adds the objects in the specified collection to this TreeSet.
    E
    ceiling(E e)
    Answers the smallest element bigger than or equal to the specified one, or null if no such element.
    void
    clear()
    Removes all elements from this TreeSet, leaving it empty.
    Comparator<? super E>
    comparator()
    Returns the comparator used to compare elements in this TreeSet.
    boolean
    contains(Object object)
    Searches this TreeSet for the specified object.
    Iterator<E>
    descendingIterator()
    Answers a descending iterator of this set.
    NavigableSet<E>
    descendingSet()
    Answers a reverse order view of this set.
    E
    first()
    Answers the first element in this TreeSet.
    E
    floor(E e)
    Answers the biggest element less than or equal to the specified one, or null if no such element.
    SortedSet<E>
    headSet(E end)
    Answers a SortedSet of the specified portion of this TreeSet which contains elements less than the end element.
    NavigableSet<E>
    headSet(E end, boolean endInclusive)
    Answers a NavigableSet of the specified portion of this set which contains elements less than (or equal to, depends on endInclusive) the end element.
    E
    higher(E e)
    Answers the smallest element bigger than the specified one, or null if no such element.
    boolean
    isEmpty()
    Returns true if this TreeSet has no element, otherwise false.
    Iterator<E>
    iterator()
    Returns an Iterator on the elements of this TreeSet.
    E
    last()
    Answers the last element in this TreeSet.
    E
    lower(E e)
    Answers the biggest element less than the specified one, or null if no such element.
    E
    pollFirst()
    Deletes and answers the smallest element, or null if the set is empty.
    E
    pollLast()
    Deletes and answers the biggest element, or null if the set is empty.
    boolean
    remove(Object object)
    Removes an occurrence of the specified object from this TreeSet.
    int
    size()
    Returns the number of elements in this TreeSet.
    NavigableSet<E>
    subSet(E start, boolean startInclusive, E end, boolean endInclusive)
    Answers a NavigableSet of the specified portion of this set which contains elements greater (or equal to, depends on startInclusive) the start element but less than (or equal to, depends on endInclusive) the end element.
    SortedSet<E>
    subSet(E start, E end)
    Answers a SortedSet of the specified portion of this TreeSet which contains elements greater or equal to the start element but less than the end element.
    SortedSet<E>
    tailSet(E start)
    Answers a SortedSet of the specified portion of this TreeSet which contains elements greater or equal to the start element.
    NavigableSet<E>
    tailSet(E start, boolean startInclusive)
    Answers a NavigableSet of the specified portion of this set which contains elements greater (or equal to, depends on startInclusive) the start element.

    Methods inherited from class AbstractSet

    equals, hashCode, removeAll

    Methods inherited from class AbstractCollection

    containsAll, retainAll, toArray, toArray, toString

    Methods inherited from class Object

    clone, getClass, notify, notifyAll, wait, wait, wait

    Methods inherited from interface Set

    containsAll, equals, hashCode, removeAll, retainAll, toArray, toArray

  • Constructor Details

    • TreeSet

      public TreeSet()
      Constructs a new empty instance of TreeSet which uses natural ordering.

    • TreeSet

      public TreeSet(Collection<? extends E> collection)
      Constructs a new instance of TreeSet which uses natural ordering and containing the unique elements in the specified collection.
      Parameters:
      collection - the collection of elements to add.
      Throws:
      ClassCastException - when an element in the collection does not implement the Comparable interface, or the elements in the collection cannot be compared.

    • TreeSet

      public TreeSet(Comparator<? super E> comparator)
      Constructs a new empty instance of TreeSet which uses the specified comparator.
      Parameters:
      comparator - the comparator to use.

    • TreeSet

      public TreeSet(SortedSet<E> set)
      Constructs a new instance of TreeSet containing the elements of the specified SortedSet and using the same Comparator.
      Parameters:
      set - the SortedSet of elements to add.

  • Method Details

    • add

      public boolean add(E object)
      Adds the specified object to this TreeSet.
      Specified by:
      add in interface Collection<E>
      Specified by:
      add in interface Set<E>
      Overrides:
      add in class AbstractCollection<E>
      Parameters:
      object - the object to add.
      Returns:
      true when this TreeSet did not already contain the object, false otherwise.
      Throws:
      ClassCastException - when the object cannot be compared with the elements in this TreeSet.
      NullPointerException - when the object is null and the comparator cannot handle null.

    • addAll

      public boolean addAll(Collection<? extends E> collection)
      Adds the objects in the specified collection to this TreeSet.
      Specified by:
      addAll in interface Collection<E>
      Specified by:
      addAll in interface Set<E>
      Overrides:
      addAll in class AbstractCollection<E>
      Parameters:
      collection - the collection of objects to add.
      Returns:
      true if this TreeSet was modified, false otherwise.
      Throws:
      ClassCastException - when an object in the collection cannot be compared with the elements in this TreeSet.
      NullPointerException - when an object in the collection is null and the comparator cannot handle null.

    • clear

      public void clear()
      Removes all elements from this TreeSet, leaving it empty.
      Specified by:
      clear in interface Collection<E>
      Specified by:
      clear in interface Set<E>
      Overrides:
      clear in class AbstractCollection<E>
      See Also:

    • comparator

      public Comparator<? super E> comparator()
      Returns the comparator used to compare elements in this TreeSet.
      Specified by:
      comparator in interface SortedSet<E>
      Returns:
      a Comparator or null if the natural ordering is used

    • contains

      public boolean contains(Object object)
      Searches this TreeSet for the specified object.
      Specified by:
      contains in interface Collection<E>
      Specified by:
      contains in interface Set<E>
      Overrides:
      contains in class AbstractCollection<E>
      Parameters:
      object - the object to search for.
      Returns:
      true if object is an element of this TreeSet, false otherwise.
      Throws:
      ClassCastException - when the object cannot be compared with the elements in this TreeSet.
      NullPointerException - when the object is null and the comparator cannot handle null.

    • isEmpty

      public boolean isEmpty()
      Returns true if this TreeSet has no element, otherwise false.
      Specified by:
      isEmpty in interface Collection<E>
      Specified by:
      isEmpty in interface Set<E>
      Overrides:
      isEmpty in class AbstractCollection<E>
      Returns:
      true if this TreeSet has no element.
      See Also:

    • iterator

      public Iterator<E> iterator()
      Returns an Iterator on the elements of this TreeSet.
      Specified by:
      iterator in interface Collection<E>
      Specified by:
      iterator in interface Iterable<E>
      Specified by:
      iterator in interface Set<E>
      Specified by:
      iterator in class AbstractCollection<E>
      Returns:
      an Iterator on the elements of this TreeSet.
      See Also:

    • descendingIterator

      public Iterator<E> descendingIterator()
      Answers a descending iterator of this set.
      Specified by:
      descendingIterator in interface NavigableSet<E>
      Returns:
      the descending iterator
      Since:
      1.6
      See Also:

    • remove

      public boolean remove(Object object)
      Removes an occurrence of the specified object from this TreeSet.
      Specified by:
      remove in interface Collection<E>
      Specified by:
      remove in interface Set<E>
      Overrides:
      remove in class AbstractCollection<E>
      Parameters:
      object - the object to remove.
      Returns:
      true if this TreeSet was modified, false otherwise.
      Throws:
      ClassCastException - when the object cannot be compared with the elements in this TreeSet.
      NullPointerException - when the object is null and the comparator cannot handle null.

    • size

      public int size()
      Returns the number of elements in this TreeSet.
      Specified by:
      size in interface Collection<E>
      Specified by:
      size in interface Set<E>
      Specified by:
      size in class AbstractCollection<E>
      Returns:
      the number of elements in this TreeSet.

    • first

      public E first()
      Answers the first element in this TreeSet.
      Specified by:
      first in interface SortedSet<E>
      Returns:
      the first element
      Throws:
      NoSuchElementException - when this TreeSet is empty

    • last

      public E last()
      Answers the last element in this TreeSet.
      Specified by:
      last in interface SortedSet<E>
      Returns:
      the last element
      Throws:
      NoSuchElementException - when this TreeSet is empty

    • pollFirst

      public E pollFirst()
      Deletes and answers the smallest element, or null if the set is empty.
      Specified by:
      pollFirst in interface NavigableSet<E>
      Returns:
      the smallest element, or null if the set is empty
      Since:
      1.6
      See Also:

    • pollLast

      public E pollLast()
      Deletes and answers the biggest element, or null if the set is empty.
      Specified by:
      pollLast in interface NavigableSet<E>
      Returns:
      the biggest element, or null if the set is empty
      Since:
      1.6
      See Also:

    • higher

      public E higher(E e)
      Answers the smallest element bigger than the specified one, or null if no such element.
      Specified by:
      higher in interface NavigableSet<E>
      Parameters:
      e - the specified element
      Returns:
      the smallest element bigger than the specified one, or null if no such element
      Since:
      1.6
      See Also:

    • lower

      public E lower(E e)
      Answers the biggest element less than the specified one, or null if no such element.
      Specified by:
      lower in interface NavigableSet<E>
      Parameters:
      e - the specified element
      Returns:
      the biggest element less than the specified one, or null if no such element
      Since:
      1.6
      See Also:

    • ceiling

      public E ceiling(E e)
      Answers the smallest element bigger than or equal to the specified one, or null if no such element.
      Specified by:
      ceiling in interface NavigableSet<E>
      Parameters:
      e - the specified element
      Returns:
      the smallest element bigger than or equal to the specified one, or null if no such element
      Since:
      1.6
      See Also:

    • floor

      public E floor(E e)
      Answers the biggest element less than or equal to the specified one, or null if no such element.
      Specified by:
      floor in interface NavigableSet<E>
      Parameters:
      e - the specified element
      Returns:
      the biggest element less than or equal to the specified one, or null if no such element
      Since:
      1.6
      See Also:

    • descendingSet

      public NavigableSet<E> descendingSet()
      Answers a reverse order view of this set.
      Specified by:
      descendingSet in interface NavigableSet<E>
      Returns:
      the reverse order view
      Since:
      1.6
      See Also:

    • subSet

      public NavigableSet<E> subSet(E start, boolean startInclusive, E end, boolean endInclusive)
      Answers a NavigableSet of the specified portion of this set which contains elements greater (or equal to, depends on startInclusive) the start element but less than (or equal to, depends on endInclusive) the end element. The returned NavigableSet is backed by this set so changes to one are reflected by the other.
      Specified by:
      subSet in interface NavigableSet<E>
      Parameters:
      start - the start element
      startInclusive - true if the start element is in the returned set
      end - the end element
      endInclusive - true if the end element is in the returned set
      Returns:
      the subset
      Since:
      1.6
      See Also:

    • headSet

      public NavigableSet<E> headSet(E end, boolean endInclusive)
      Answers a NavigableSet of the specified portion of this set which contains elements less than (or equal to, depends on endInclusive) the end element. The returned NavigableSet is backed by this set so changes to one are reflected by the other.
      Specified by:
      headSet in interface NavigableSet<E>
      Parameters:
      end - the end element
      endInclusive - true if the end element is in the returned set
      Returns:
      the subset
      Since:
      1.6
      See Also:

    • tailSet

      public NavigableSet<E> tailSet(E start, boolean startInclusive)
      Answers a NavigableSet of the specified portion of this set which contains elements greater (or equal to, depends on startInclusive) the start element. The returned NavigableSet is backed by this set so changes to one are reflected by the other.
      Specified by:
      tailSet in interface NavigableSet<E>
      Parameters:
      start - the start element
      startInclusive - true if the start element is in the returned set
      Returns:
      the subset
      Since:
      1.6
      See Also:

    • subSet

      public SortedSet<E> subSet(E start, E end)
      Answers a SortedSet of the specified portion of this TreeSet which contains elements greater or equal to the start element but less than the end element. The returned SortedSet is backed by this TreeSet so changes to one are reflected by the other.
      Specified by:
      subSet in interface SortedSet<E>
      Parameters:
      start - the start element
      end - the end element
      Returns:
      a subset where the elements are greater or equal to start and less than end
      Throws:
      ClassCastException - when the start or end object cannot be compared with the elements in this TreeSet
      NullPointerException - when the start or end object is null and the comparator cannot handle null

    • headSet

      public SortedSet<E> headSet(E end)
      Answers a SortedSet of the specified portion of this TreeSet which contains elements less than the end element. The returned SortedSet is backed by this TreeSet so changes to one are reflected by the other.
      Specified by:
      headSet in interface SortedSet<E>
      Parameters:
      end - the end element
      Returns:
      a subset where the elements are less than end
      Throws:
      ClassCastException - when the end object cannot be compared with the elements in this TreeSet
      NullPointerException - when the end object is null and the comparator cannot handle null

    • tailSet

      public SortedSet<E> tailSet(E start)
      Answers a SortedSet of the specified portion of this TreeSet which contains elements greater or equal to the start element. The returned SortedSet is backed by this TreeSet so changes to one are reflected by the other.
      Specified by:
      tailSet in interface SortedSet<E>
      Parameters:
      start - the start element
      Returns:
      a subset where the elements are greater or equal to start
      Throws:
      ClassCastException - when the start object cannot be compared with the elements in this TreeSet
      NullPointerException - when the start object is null and the comparator cannot handle null