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FlexDoc/Javadoc 2.0 Demo Java Doc |
Class TreeSet<E>
java.util.TreeSet<E>
Type Parameters:
E - the type of elements maintained by this set
All Implemented Interfaces:
public class TreeSet<E>
A
NavigableSet implementation based on a
TreeMap.
The elements are ordered using their
natural
ordering, or by a
Comparator provided at set creation
time, depending on which constructor is used.
This implementation provides guaranteed log(n) time cost for the basic
operations (add, remove and contains).
Note that the ordering maintained by a set (whether or not an explicit
comparator is provided) must be consistent with equals if it is to
correctly implement the Set interface. (See Comparable
or Comparator for a precise definition of consistent with
equals.) This is so because the Set interface is defined in
terms of the equals operation, but a TreeSet instance
performs all element comparisons using its compareTo (or
compare) method, so two elements that are deemed equal by this method
are, from the standpoint of the set, equal. The behavior of a set
is well-defined even if its ordering is inconsistent with equals; it
just fails to obey the general contract of the Set interface.
Note that this implementation is not synchronized.
If multiple threads access a tree set concurrently, and at least one
of the threads modifies the set, it must be synchronized
externally. This is typically accomplished by synchronizing on some
object that naturally encapsulates the set.
If no such object exists, the set should be "wrapped" using the
Collections.synchronizedSortedSet
method. This is best done at creation time, to prevent accidental
unsynchronized access to the set:
SortedSet s = Collections.synchronizedSortedSet(new TreeSet(...));
The iterators returned by this class's iterator method are
fail-fast: if the set is modified at any time after the iterator is
created, in any way except through the iterator's own remove
method, the iterator will throw a ConcurrentModificationException.
Thus, in the face of concurrent modification, the iterator fails quickly
and cleanly, rather than risking arbitrary, non-deterministic behavior at
an undetermined time in the future.
Note that the fail-fast behavior of an iterator cannot be guaranteed
as it is, generally speaking, impossible to make any hard guarantees in the
presence of unsynchronized concurrent modification. Fail-fast iterators
throw ConcurrentModificationException on a best-effort basis.
Therefore, it would be wrong to write a program that depended on this
exception for its correctness: the fail-fast behavior of iterators
should be used only to detect bugs.
This class is a member of the
Java Collections Framework.
Since:
1.2
Author:
Josh Bloch
See Also:
Constructor Summary |
Constructs a new, empty tree set, sorted according to the
natural ordering of its elements.
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Constructs a new tree set containing the elements in the specified
collection, sorted according to the natural ordering of its
elements.
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Constructs a new, empty tree set, sorted according to the specified
comparator.
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Constructs a new tree set containing the same elements and
using the same ordering as the specified sorted set.
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Method Summary |
boolean |
Adds the specified element to this set if it is not already present.
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boolean |
Adds all of the elements in the specified collection to this set.
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Returns the least element in this set greater than or equal to
the given element, or null if there is no such element.
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void |
Removes all of the elements from this set.
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Returns a shallow copy of this TreeSet instance.
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Returns the comparator used to order the elements in this set,
or null if this set uses the natural ordering of its elements.
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boolean |
Returns true if this set contains the specified element.
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Returns an iterator over the elements in this set in descending order.
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Returns a reverse order view of the elements contained in this set.
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Returns the first (lowest) element currently in this set.
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Returns the greatest element in this set less than or equal to
the given element, or null if there is no such element.
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Returns a view of the portion of this set whose elements are
strictly less than toElement.
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Returns a view of the portion of this set whose elements are less than
(or equal to, if inclusive is true) toElement.
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Returns the least element in this set strictly greater than the
given element, or null if there is no such element.
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boolean |
Returns true if this set contains no elements.
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Returns an iterator over the elements in this set in ascending order.
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Returns the last (highest) element currently in this set.
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Returns the greatest element in this set strictly less than the
given element, or null if there is no such element.
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Retrieves and removes the first (lowest) element,
or returns null if this set is empty.
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Retrieves and removes the last (highest) element,
or returns null if this set is empty.
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boolean |
Removes the specified element from this set if it is present.
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int |
Returns the number of elements in this set (its cardinality).
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subSet( E fromElement, boolean fromInclusive, E toElement, boolean toInclusive)
Returns a view of the portion of this set whose elements range from
fromElement to toElement.
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Returns a view of the portion of this set whose elements range
from fromElement, inclusive, to toElement,
exclusive.
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Returns a view of the portion of this set whose elements are
greater than or equal to fromElement.
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tailSet( E fromElement, boolean inclusive)
Returns a view of the portion of this set whose elements are greater
than (or equal to, if inclusive is true) fromElement.
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Methods inherited from class java.lang. Object |
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Methods inherited from interface java.util. Collection |
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Methods inherited from interface java.lang. Iterable |
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Methods inherited from interface java.util. Set |
copyOf, of, of, of, of, of, of, of, of, of, of, of, of |
Constructs a new, empty tree set, sorted according to the
natural ordering of its elements. All elements inserted into
the set must implement the
Comparable interface.
Furthermore, all such elements must be
mutually
comparable:
e1.compareTo(e2) must not throw a
ClassCastException for any elements
e1 and
e2 in the set. If the user attempts to add an element
to the set that violates this constraint (for example, the user
attempts to add a string element to a set whose elements are
integers), the
add call will throw a
ClassCastException.
Constructs a new, empty tree set, sorted according to the specified
comparator. All elements inserted into the set must be
mutually
comparable by the specified comparator:
comparator.compare(e1,
e2) must not throw a
ClassCastException for any elements
e1 and
e2 in the set. If the user attempts to add
an element to the set that violates this constraint, the
add call will throw a
ClassCastException.
Parameters:
comparator - the comparator that will be used to order this set.
If
null, the
natural
ordering of the elements will be used.
Constructs a new tree set containing the elements in the specified
collection, sorted according to the
natural ordering of its
elements. All elements inserted into the set must implement the
Comparable interface. Furthermore, all such elements must be
mutually comparable:
e1.compareTo(e2) must not throw a
ClassCastException for any elements
e1 and
e2 in the set.
Parameters:
c - collection whose elements will comprise the new set
Throws:
Constructs a new tree set containing the same elements and
using the same ordering as the specified sorted set.
Parameters:
s - sorted set whose elements will comprise the new set
Throws:
Returns an iterator over the elements in this set in ascending order.
Specified by:
Overrides:
Returns:
an iterator over the elements in this set in ascending order
Returns an iterator over the elements in this set in descending order.
Specified by:
Returns:
an iterator over the elements in this set in descending order
Since:
1.6
Returns a reverse order view of the elements contained in this set.
The descending set is backed by this set, so changes to the set are
reflected in the descending set, and vice-versa. If either set is
modified while an iteration over either set is in progress (except
through the iterator's own
remove operation), the results of
the iteration are undefined.
The returned set has an ordering equivalent to
Collections.reverseOrder(comparator()).
The expression s.descendingSet().descendingSet() returns a
view of s essentially equivalent to s.
Specified by:
Returns:
a reverse order view of this set
Since:
1.6
Returns the number of elements in this set (its cardinality).
Specified by:
Overrides:
Returns:
the number of elements in this set (its cardinality)
public boolean isEmpty |
() |
Returns
true if this set contains no elements.
Specified by:
Overrides:
Returns:
true if this set contains no elements
Returns
true if this set contains the specified element.
More formally, returns
true if and only if this set
contains an element
e such that
Objects.equals(o, e).
Specified by:
Overrides:
Parameters:
o - object to be checked for containment in this set
Returns:
true if this set contains the specified element
Throws:
ClassCastException - if the specified object cannot be compared
with the elements currently in the set
NullPointerException - if the specified element is null
and this set uses natural ordering, or its comparator
does not permit null elements
Adds the specified element to this set if it is not already present.
More formally, adds the specified element
e to this set if
the set contains no element
e2 such that
Objects.equals(e, e2).
If this set already contains the element, the call leaves the set
unchanged and returns
false.
Specified by:
Overrides:
Parameters:
e - element to be added to this set
Returns:
true if this set did not already contain the specified
element
Throws:
ClassCastException - if the specified object cannot be compared
with the elements currently in this set
NullPointerException - if the specified element is null
and this set uses natural ordering, or its comparator
does not permit null elements
Removes the specified element from this set if it is present.
More formally, removes an element
e such that
Objects.equals(o, e),
if this set contains such an element. Returns
true if
this set contained the element (or equivalently, if this set
changed as a result of the call). (This set will not contain the
element once the call returns.)
Specified by:
Overrides:
Parameters:
o - object to be removed from this set, if present
Returns:
true if this set contained the specified element
Throws:
ClassCastException - if the specified object cannot be compared
with the elements currently in this set
NullPointerException - if the specified element is null
and this set uses natural ordering, or its comparator
does not permit null elements
Removes all of the elements from this set.
The set will be empty after this call returns.
Specified by:
Overrides:
Adds all of the elements in the specified collection to this set.
Specified by:
Overrides:
Parameters:
c - collection containing elements to be added to this set
Returns:
true if this set changed as a result of the call
Throws:
ClassCastException - if the elements provided cannot be compared
with the elements currently in the set
NullPointerException - if the specified collection is null or
if any element is null and this set uses natural ordering, or
its comparator does not permit null elements
See Also:
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( E fromElement, boolean fromInclusive, E toElement, boolean toInclusive) |
Returns a view of the portion of this set whose elements range from
fromElement to
toElement. If
fromElement and
toElement are equal, the returned set is empty unless
fromInclusive and
toInclusive are both true. The returned set
is backed by this set, so changes in the returned set are reflected in
this set, and vice-versa. The returned set supports all optional set
operations that this set supports.
The returned set will throw an IllegalArgumentException
on an attempt to insert an element outside its range.
Specified by:
Parameters:
fromElement - low endpoint of the returned set
fromInclusive - true if the low endpoint
is to be included in the returned view
toElement - high endpoint of the returned set
toInclusive - true if the high endpoint
is to be included in the returned view
Returns:
a view of the portion of this set whose elements range from
fromElement, inclusive, to toElement, exclusive
Throws:
ClassCastException - if
fromElement and
toElement cannot be compared to one another using this
set's comparator (or, if the set has no comparator, using
natural ordering). Implementations may, but are not required
to, throw this exception if
fromElement or
toElement cannot be compared to elements currently in
the set.
NullPointerException - if
fromElement or
toElement
is null and this set uses natural ordering, or its comparator
does not permit null elements
IllegalArgumentException - if
fromElement is
greater than
toElement; or if this set itself
has a restricted range, and
fromElement or
toElement lies outside the bounds of the range.
Since:
1.6
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( E toElement, boolean inclusive) |
Returns a view of the portion of this set whose elements are less than
(or equal to, if
inclusive is true)
toElement. The
returned set is backed by this set, so changes in the returned set are
reflected in this set, and vice-versa. The returned set supports all
optional set operations that this set supports.
The returned set will throw an IllegalArgumentException
on an attempt to insert an element outside its range.
Specified by:
Parameters:
toElement - high endpoint of the returned set
inclusive - true if the high endpoint
is to be included in the returned view
Returns:
a view of the portion of this set whose elements are less than
(or equal to, if inclusive is true) toElement
Throws:
ClassCastException - if
toElement is not compatible
with this set's comparator (or, if the set has no comparator,
if
toElement does not implement
Comparable).
Implementations may, but are not required to, throw this
exception if
toElement cannot be compared to elements
currently in the set.
NullPointerException - if
toElement is null and
this set uses natural ordering, or its comparator does
not permit null elements
IllegalArgumentException - if this set itself has a
restricted range, and
toElement lies outside the
bounds of the range
Since:
1.6
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( E fromElement, boolean inclusive) |
Returns a view of the portion of this set whose elements are greater
than (or equal to, if
inclusive is true)
fromElement.
The returned set is backed by this set, so changes in the returned set
are reflected in this set, and vice-versa. The returned set supports
all optional set operations that this set supports.
The returned set will throw an IllegalArgumentException
on an attempt to insert an element outside its range.
Specified by:
Parameters:
fromElement - low endpoint of the returned set
inclusive - true if the low endpoint
is to be included in the returned view
Returns:
a view of the portion of this set whose elements are greater
than or equal to fromElement
Throws:
ClassCastException - if
fromElement is not compatible
with this set's comparator (or, if the set has no comparator,
if
fromElement does not implement
Comparable).
Implementations may, but are not required to, throw this
exception if
fromElement cannot be compared to elements
currently in the set.
NullPointerException - if
fromElement is null and
this set uses natural ordering, or its comparator does
not permit null elements
IllegalArgumentException - if this set itself has a
restricted range, and
fromElement lies outside the
bounds of the range
Since:
1.6
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( E fromElement, E toElement) |
Returns a view of the portion of this set whose elements range
from
fromElement, inclusive, to
toElement,
exclusive. (If
fromElement and
toElement are
equal, the returned set is empty.) The returned set is backed
by this set, so changes in the returned set are reflected in
this set, and vice-versa. The returned set supports all
optional set operations that this set supports.
The returned set will throw an IllegalArgumentException
on an attempt to insert an element outside its range.
Equivalent to subSet(fromElement, true, toElement, false).
Specified by:
Parameters:
fromElement - low endpoint (inclusive) of the returned set
toElement - high endpoint (exclusive) of the returned set
Returns:
a view of the portion of this set whose elements range from
fromElement, inclusive, to toElement, exclusive
Throws:
ClassCastException - if
fromElement and
toElement cannot be compared to one another using this
set's comparator (or, if the set has no comparator, using
natural ordering). Implementations may, but are not required
to, throw this exception if
fromElement or
toElement cannot be compared to elements currently in
the set.
NullPointerException - if
fromElement or
toElement is null and this set uses natural ordering,
or its comparator does not permit null elements
IllegalArgumentException - if
fromElement is
greater than
toElement; or if this set itself
has a restricted range, and
fromElement or
toElement lies outside the bounds of the range
Returns a view of the portion of this set whose elements are
strictly less than
toElement. The returned set is
backed by this set, so changes in the returned set are
reflected in this set, and vice-versa. The returned set
supports all optional set operations that this set supports.
The returned set will throw an IllegalArgumentException
on an attempt to insert an element outside its range.
Equivalent to headSet(toElement, false).
Specified by:
Parameters:
toElement - high endpoint (exclusive) of the returned set
Returns:
a view of the portion of this set whose elements are strictly
less than toElement
Throws:
ClassCastException - if
toElement is not compatible
with this set's comparator (or, if the set has no comparator,
if
toElement does not implement
Comparable).
Implementations may, but are not required to, throw this
exception if
toElement cannot be compared to elements
currently in the set.
NullPointerException - if
toElement is null
and this set uses natural ordering, or its comparator does
not permit null elements
IllegalArgumentException - if this set itself has a
restricted range, and
toElement lies outside the
bounds of the range
Returns a view of the portion of this set whose elements are
greater than or equal to
fromElement. The returned
set is backed by this set, so changes in the returned set are
reflected in this set, and vice-versa. The returned set
supports all optional set operations that this set supports.
The returned set will throw an IllegalArgumentException
on an attempt to insert an element outside its range.
Equivalent to tailSet(fromElement, true).
Specified by:
Parameters:
fromElement - low endpoint (inclusive) of the returned set
Returns:
a view of the portion of this set whose elements are greater
than or equal to fromElement
Throws:
ClassCastException - if
fromElement is not compatible
with this set's comparator (or, if the set has no comparator,
if
fromElement does not implement
Comparable).
Implementations may, but are not required to, throw this
exception if
fromElement cannot be compared to elements
currently in the set.
NullPointerException - if
fromElement is null
and this set uses natural ordering, or its comparator does
not permit null elements
IllegalArgumentException - if this set itself has a
restricted range, and
fromElement lies outside the
bounds of the range
Returns the comparator used to order the elements in this set,
or
null if this set uses the
natural ordering of its elements.
Specified by:
Returns:
the comparator used to order the elements in this set,
or null if this set uses the natural ordering
of its elements
Returns the first (lowest) element currently in this set.
Specified by:
Returns:
the first (lowest) element currently in this set
Throws:
Returns the last (highest) element currently in this set.
Specified by:
Returns:
the last (highest) element currently in this set
Throws:
Returns the greatest element in this set strictly less than the
given element, or null if there is no such element.
Specified by:
Parameters:
e - the value to match
Returns:
the greatest element less than e,
or null if there is no such element
Throws:
ClassCastException - if the specified element cannot be
compared with the elements currently in the set
NullPointerException - if the specified element is null
and this set uses natural ordering, or its comparator
does not permit null elements
Since:
1.6
Returns the greatest element in this set less than or equal to
the given element, or null if there is no such element.
Specified by:
Parameters:
e - the value to match
Returns:
the greatest element less than or equal to e,
or null if there is no such element
Throws:
ClassCastException - if the specified element cannot be
compared with the elements currently in the set
NullPointerException - if the specified element is null
and this set uses natural ordering, or its comparator
does not permit null elements
Since:
1.6
Returns the least element in this set greater than or equal to
the given element, or null if there is no such element.
Specified by:
Parameters:
e - the value to match
Returns:
the least element greater than or equal to e,
or null if there is no such element
Throws:
ClassCastException - if the specified element cannot be
compared with the elements currently in the set
NullPointerException - if the specified element is null
and this set uses natural ordering, or its comparator
does not permit null elements
Since:
1.6
Returns the least element in this set strictly greater than the
given element, or null if there is no such element.
Specified by:
Parameters:
e - the value to match
Returns:
the least element greater than e,
or null if there is no such element
Throws:
ClassCastException - if the specified element cannot be
compared with the elements currently in the set
NullPointerException - if the specified element is null
and this set uses natural ordering, or its comparator
does not permit null elements
Since:
1.6
Retrieves and removes the first (lowest) element,
or returns null if this set is empty.
Specified by:
Returns:
the first element, or null if this set is empty
Since:
1.6
Retrieves and removes the last (highest) element,
or returns null if this set is empty.
Specified by:
Returns:
the last element, or null if this set is empty
Since:
1.6
Returns a shallow copy of this
TreeSet instance. (The elements
themselves are not cloned.)
Overrides:
Returns:
a shallow copy of this set
See Also:
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