java.util.SortedSet Maven / Gradle / Ivy
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This work corresponds to the API signatures of JSR 219: Foundation
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*/
package java.util;
/**
* A set that further guarantees that its iterator will traverse the set in
* ascending element order, sorted according to the natural ordering of
* its elements (see Comparable), or by a Comparator provided at sorted set
* creation time. Several additional operations are provided to take
* advantage of the ordering. (This interface is the set analogue of
* SortedMap.)
*
* All elements inserted into an 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 order 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 elements' natural ordering. 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) but the SDK implementation (the
* TreeSet class) complies.
*
* This interface is a member of the
*
* Java Collections Framework.
*
* @author Josh Bloch
* @version 1.15, 02/02/00
* @see Set
* @see TreeSet
* @see SortedMap
* @see Collection
* @see Comparable
* @see Comparator
* @see java.lang.ClassCastException
* @since 1.2
*/
public interface SortedSet extends Set
{
/**
* Returns the comparator associated with this sorted set, or
* null if it uses its elements' natural ordering.
*
* @return the comparator associated with this sorted set, or
* null if it uses its elements' natural ordering.
*/
public Comparator comparator();
/**
* Returns a view of the portion of this sorted set whose elements range
* from fromElement, inclusive, to toElement, exclusive.
* (If fromElement and toElement are equal, the returned
* sorted set is empty.) The returned sorted set is backed by this sorted
* set, so changes in the returned sorted set are reflected in this sorted
* set, and vice-versa. The returned sorted set supports all optional set
* operations that this sorted set supports.
*
* The sorted set returned by this method will throw an
* IllegalArgumentException if the user attempts to insert a
* element outside the specified range.
*
* Note: this method always returns a half-open range (which
* includes its low endpoint but not its high endpoint). If you need a
* closed range (which includes both endpoints), and the element
* type allows for calculation of the successor 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 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 sub = s.subSet(low+"\0", high);
*
*
* @param fromElement low endpoint (inclusive) of the subSet.
* @param toElement high endpoint (exclusive) of the subSet.
* @return a view of the specified range within this sorted 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.
* @throws IllegalArgumentException if fromElement is greater than
* toElement; or if this set is itself a subSet, headSet,
* or tailSet, and fromElement or toElement are
* not within the specified range of the subSet, headSet, or
* tailSet.
* @throws NullPointerException if fromElement or
* toElement is null and this sorted set does
* not tolerate null elements.
*/
public SortedSet subSet(Object fromElement, Object toElement);
/**
* Returns a view of the portion of this sorted set whose elements are
* strictly less than toElement. The returned sorted set is
* backed by this sorted set, so changes in the returned sorted set are
* reflected in this sorted set, and vice-versa. The returned sorted set
* supports all optional set operations.
*
* The sorted set returned by this method will throw an
* IllegalArgumentException if the user attempts to insert a
* element outside the specified range.
*
* Note: this method always returns a view that does not contain its
* (high) endpoint. If you need a view that does contain this endpoint,
* and the element type allows for calculation of the successor a given
* value, merely request a headSet bounded by
* 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 that are less than or equal
* to high:
*
SortedSet head = s.headSet(high+"\0");
*
* @param toElement high endpoint (exclusive) of the headSet.
* @return a view of the specified initial range of this sorted 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.
* @throws NullPointerException if toElement is null and
* this sorted set does not tolerate null elements.
* @throws IllegalArgumentException if this set is itself a subSet,
* headSet, or tailSet, and toElement is not within the
* specified range of the subSet, headSet, or tailSet.
*/
public SortedSet headSet(Object toElement);
/**
* Returns a view of the portion of this sorted set whose elements are
* greater than or equal to fromElement. The returned sorted set
* is backed by this sorted set, so changes in the returned sorted set are
* reflected in this sorted set, and vice-versa. The returned sorted set
* supports all optional set operations.
*
* The sorted set returned by this method will throw an
* IllegalArgumentException if the user attempts to insert a
* element outside the specified range.
*
* Note: this method always returns a view that contains its (low)
* endpoint. If you need a view that does not contain this endpoint, and
* the element type allows for calculation of the successor a given value,
* merely request a tailSet bounded by successor(lowEndpoint).
* For example, suppose that s is a sorted set of strings. The
* following idiom obtains a view containing all of the strings in
* s that are strictly greater than low:
*
*
SortedSet tail = s.tailSet(low+"\0");
*
* @param fromElement low endpoint (inclusive) of the tailSet.
* @return a view of the specified final range of this sorted 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.
* @throws NullPointerException if fromElement is null
* and this sorted set does not tolerate null elements.
* @throws IllegalArgumentException if this set is itself a subSet,
* headSet, or tailSet, and fromElement is not within the
* specified range of the subSet, headSet, or tailSet.
*/
public SortedSet tailSet(Object fromElement);
/**
* Returns the first (lowest) element currently in this sorted set.
*
* @return the first (lowest) element currently in this sorted set.
* @throws NoSuchElementException sorted set is empty.
*/
public Object first();
/**
* Returns the last (highest) element currently in this sorted set.
*
* @return the last (highest) element currently in this sorted set.
* @throws NoSuchElementException sorted set is empty.
*/
public Object last();
}