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package java.util;
A Set that further provides a total ordering on its elements. The elements are ordered using their natural
ordering, or by a Comparator typically provided at sorted set creation time. The set's iterator will traverse the set in ascending element order. Several additional operations are provided to take advantage of the ordering. (This interface is the set analogue of SortedMap.) All elements inserted into a sorted set must implement the Comparable interface (or be accepted by the specified comparator). Furthermore, all such elements must be mutually comparable: e1.compareTo(e2) (or comparator.compare(e1, e2)) must not throw a ClassCastException for any elements e1 and e2 in the sorted set. Attempts to violate this restriction will cause the offending method or constructor invocation to throw a ClassCastException.
Note that the ordering maintained by a sorted set (whether or not an
explicit comparator is provided) must be consistent with equals if the sorted set is to correctly implement the Set interface. (See the Comparable interface or Comparator interface 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 sorted set 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 sorted set, equal. The behavior of a sorted set is well-defined even if its ordering is inconsistent with equals; it just fails to obey the general contract of the Set interface.
All general-purpose sorted set implementation classes should provide four "standard" constructors: 1) A void (no arguments) constructor, which creates an empty sorted set sorted according to the natural ordering of its elements. 2) A constructor with a single argument of type Comparator, which creates an empty sorted set sorted according to the specified comparator. 3) A constructor with a single argument of type Collection, which creates a new sorted set with the same elements as its argument, sorted according to the natural ordering of the elements. 4) A constructor with a single argument of type SortedSet, which creates a new sorted set with the same elements and the same ordering as the input sorted set. There is no way to enforce this recommendation, as interfaces cannot contain constructors.
Note: several methods return subsets with restricted ranges.
Such ranges are half-open, that is, they include their low
endpoint but not their high endpoint (where applicable).
If you need a closed range (which includes both endpoints), and the element type allows for calculation of the successor of a given value, merely request the subrange from lowEndpoint to successor(highEndpoint). For example, suppose that s is a sorted set of strings. The following idiom obtains a view containing all of the strings in s from low to high, inclusive:
SortedSet<String> sub = s.subSet(low, high+"\0");
A similar technique can be used to generate an open range (which contains neither endpoint). The following idiom obtains a view containing all of the Strings in s from low to high, exclusive: SortedSet<String> sub = s.subSet(low+"\0", high);
This interface is a member of the
Java Collections Framework.
Author: Josh Bloch Type parameters: - <E> – the type of elements maintained by this set
See Also: Since: 1.2
/**
* A {@link Set} that further provides a <i>total ordering</i> on its elements.
* The elements are ordered using their {@linkplain Comparable natural
* ordering}, or by a {@link Comparator} typically provided at sorted
* set creation time. The set's iterator will traverse the set in
* ascending element order. Several additional operations are provided
* to take advantage of the ordering. (This interface is the set
* analogue of {@link SortedMap}.)
*
* <p>All elements inserted into a sorted set must implement the {@code Comparable}
* interface (or be accepted by the specified comparator). Furthermore, all
* such elements must be <i>mutually comparable</i>: {@code e1.compareTo(e2)}
* (or {@code comparator.compare(e1, e2)}) must not throw a
* {@code ClassCastException} for any elements {@code e1} and {@code e2} in
* the sorted set. Attempts to violate this restriction will cause the
* offending method or constructor invocation to throw a
* {@code ClassCastException}.
*
* <p>Note that the ordering maintained by a sorted set (whether or not an
* explicit comparator is provided) must be <i>consistent with equals</i> if
* the sorted set is to correctly implement the {@code Set} interface. (See
* the {@code Comparable} interface or {@code Comparator} interface for a
* precise definition of <i>consistent with equals</i>.) This is so because
* the {@code Set} interface is defined in terms of the {@code equals}
* operation, but a sorted set performs all element comparisons using its
* {@code compareTo} (or {@code compare}) method, so two elements that are
* deemed equal by this method are, from the standpoint of the sorted set,
* equal. The behavior of a sorted set <i>is</i> well-defined even if its
* ordering is inconsistent with equals; it just fails to obey the general
* contract of the {@code Set} interface.
*
* <p>All general-purpose sorted set implementation classes should
* provide four "standard" constructors: 1) A void (no arguments)
* constructor, which creates an empty sorted set sorted according to
* the natural ordering of its elements. 2) A constructor with a
* single argument of type {@code Comparator}, which creates an empty
* sorted set sorted according to the specified comparator. 3) A
* constructor with a single argument of type {@code Collection},
* which creates a new sorted set with the same elements as its
* argument, sorted according to the natural ordering of the elements.
* 4) A constructor with a single argument of type {@code SortedSet},
* which creates a new sorted set with the same elements and the same
* ordering as the input sorted set. There is no way to enforce this
* recommendation, as interfaces cannot contain constructors.
*
* <p>Note: several methods return subsets with restricted ranges.
* Such ranges are <i>half-open</i>, that is, they include their low
* endpoint but not their high endpoint (where applicable).
* If you need a <i>closed range</i> (which includes both endpoints), and
* the element type allows for calculation of the successor of a given
* value, merely request the subrange from {@code lowEndpoint} to
* {@code successor(highEndpoint)}. For example, suppose that {@code s}
* is a sorted set of strings. The following idiom obtains a view
* containing all of the strings in {@code s} from {@code low} to
* {@code high}, inclusive:<pre>
* SortedSet<String> sub = s.subSet(low, high+"\0");</pre>
*
* A similar technique can be used to generate an <i>open range</i> (which
* contains neither endpoint). The following idiom obtains a view
* containing all of the Strings in {@code s} from {@code low} to
* {@code high}, exclusive:<pre>
* SortedSet<String> sub = s.subSet(low+"\0", high);</pre>
*
* <p>This interface is a member of the
* <a href="{@docRoot}/java.base/java/util/package-summary.html#CollectionsFramework">
* Java Collections Framework</a>.
*
* @param <E> the type of elements maintained by this set
*
* @author Josh Bloch
* @see Set
* @see TreeSet
* @see SortedMap
* @see Collection
* @see Comparable
* @see Comparator
* @see ClassCastException
* @since 1.2
*/
public interface SortedSet<E> extends Set<E> {
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 comparator used to order the elements in this set, or null if this set uses the natural ordering of its elements
/**
* Returns the comparator used to order the elements in this set,
* or {@code null} if this set uses the {@linkplain Comparable
* natural ordering} of its elements.
*
* @return the comparator used to order the elements in this set,
* or {@code null} if this set uses the natural ordering
* of its elements
*/
Comparator<? super E> comparator();
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.
Params: - fromElement – low endpoint (inclusive) of the returned set
- toElement – high endpoint (exclusive) of the returned set
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 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 range from fromElement, inclusive, to toElement, exclusive
/**
* Returns a view of the portion of this set whose elements range
* from {@code fromElement}, inclusive, to {@code toElement},
* exclusive. (If {@code fromElement} and {@code 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.
*
* <p>The returned set will throw an {@code IllegalArgumentException}
* on an attempt to insert an element outside its range.
*
* @param fromElement low endpoint (inclusive) of the returned set
* @param toElement high endpoint (exclusive) of the returned set
* @return a view of the portion of this set whose elements range from
* {@code fromElement}, inclusive, to {@code toElement}, exclusive
* @throws ClassCastException if {@code fromElement} and
* {@code 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 {@code fromElement} or
* {@code toElement} cannot be compared to elements currently in
* the set.
* @throws NullPointerException if {@code fromElement} or
* {@code toElement} is null and this set does not permit null
* elements
* @throws IllegalArgumentException if {@code fromElement} is
* greater than {@code toElement}; or if this set itself
* has a restricted range, and {@code fromElement} or
* {@code toElement} lies outside the bounds of the range
*/
SortedSet<E> subSet(E fromElement, E toElement);
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.
Params: - toElement – high endpoint (exclusive) of the returned set
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 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 strictly less than toElement
/**
* Returns a view of the portion of this set whose elements are
* strictly less than {@code 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.
*
* <p>The returned set will throw an {@code IllegalArgumentException}
* on an attempt to insert an element outside its range.
*
* @param toElement high endpoint (exclusive) of the returned set
* @return a view of the portion of this set whose elements are strictly
* less than {@code toElement}
* @throws ClassCastException if {@code toElement} is not compatible
* with this set's comparator (or, if the set has no comparator,
* if {@code toElement} does not implement {@link Comparable}).
* Implementations may, but are not required to, throw this
* exception if {@code toElement} cannot be compared to elements
* currently in the set.
* @throws NullPointerException if {@code toElement} is null and
* this set does not permit null elements
* @throws IllegalArgumentException if this set itself has a
* restricted range, and {@code toElement} lies outside the
* bounds of the range
*/
SortedSet<E> headSet(E toElement);
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.
Params: - fromElement – low endpoint (inclusive) of the returned set
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 does not permit null elements - IllegalArgumentException – if this set itself has a restricted range, and
fromElement 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
/**
* Returns a view of the portion of this set whose elements are
* greater than or equal to {@code 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.
*
* <p>The returned set will throw an {@code IllegalArgumentException}
* on an attempt to insert an element outside its range.
*
* @param fromElement low endpoint (inclusive) of the returned set
* @return a view of the portion of this set whose elements are greater
* than or equal to {@code fromElement}
* @throws ClassCastException if {@code fromElement} is not compatible
* with this set's comparator (or, if the set has no comparator,
* if {@code fromElement} does not implement {@link Comparable}).
* Implementations may, but are not required to, throw this
* exception if {@code fromElement} cannot be compared to elements
* currently in the set.
* @throws NullPointerException if {@code fromElement} is null
* and this set does not permit null elements
* @throws IllegalArgumentException if this set itself has a
* restricted range, and {@code fromElement} lies outside the
* bounds of the range
*/
SortedSet<E> tailSet(E fromElement);
Returns the first (lowest) element currently in this set.
Throws: - NoSuchElementException – if this set is empty
Returns: the first (lowest) element currently in this set
/**
* Returns the first (lowest) element currently in this set.
*
* @return the first (lowest) element currently in this set
* @throws NoSuchElementException if this set is empty
*/
E first();
Returns the last (highest) element currently in this set.
Throws: - NoSuchElementException – if this set is empty
Returns: the last (highest) element currently in this set
/**
* Returns the last (highest) element currently in this set.
*
* @return the last (highest) element currently in this set
* @throws NoSuchElementException if this set is empty
*/
E last();
Creates a Spliterator over the elements in this sorted set. The Spliterator reports Spliterator.DISTINCT, Spliterator.SORTED and Spliterator.ORDERED. Implementations should document the reporting of additional characteristic values.
The spliterator's comparator (see Spliterator.getComparator()) must be null if the sorted set's comparator (see comparator()) is null. Otherwise, the spliterator's comparator must be the same as or impose the same total ordering as the sorted set's comparator.
Implementation Requirements:
The default implementation creates a
late-binding spliterator from the sorted set's Iterator. The spliterator inherits the fail-fast properties of the set's iterator. The
spliterator's comparator is the same as the sorted set's comparator.
The created Spliterator additionally reports Spliterator.SIZED.
Implementation Note: The created Spliterator additionally reports Spliterator.SUBSIZED. Returns: a Spliterator over the elements in this sorted set Since: 1.8
/**
* Creates a {@code Spliterator} over the elements in this sorted set.
*
* <p>The {@code Spliterator} reports {@link Spliterator#DISTINCT},
* {@link Spliterator#SORTED} and {@link Spliterator#ORDERED}.
* Implementations should document the reporting of additional
* characteristic values.
*
* <p>The spliterator's comparator (see
* {@link java.util.Spliterator#getComparator()}) must be {@code null} if
* the sorted set's comparator (see {@link #comparator()}) is {@code null}.
* Otherwise, the spliterator's comparator must be the same as or impose the
* same total ordering as the sorted set's comparator.
*
* @implSpec
* The default implementation creates a
* <em><a href="Spliterator.html#binding">late-binding</a></em> spliterator
* from the sorted set's {@code Iterator}. The spliterator inherits the
* <em>fail-fast</em> properties of the set's iterator. The
* spliterator's comparator is the same as the sorted set's comparator.
* <p>
* The created {@code Spliterator} additionally reports
* {@link Spliterator#SIZED}.
*
* @implNote
* The created {@code Spliterator} additionally reports
* {@link Spliterator#SUBSIZED}.
*
* @return a {@code Spliterator} over the elements in this sorted set
* @since 1.8
*/
@Override
default Spliterator<E> spliterator() {
return new Spliterators.IteratorSpliterator<E>(
this, Spliterator.DISTINCT | Spliterator.SORTED | Spliterator.ORDERED) {
@Override
public Comparator<? super E> getComparator() {
return SortedSet.this.comparator();
}
};
}
}