java::util::SortedSet Class Reference

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java::util::TreeSetjava::util::Setjava::util::Collectionjava::lang::Interfacejava::lang::Object
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Collaboration diagram for java::util::SortedSet:

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java::util::Setjava::util::Collectionjava::lang::Interfacejava::lang::Object
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List of all members.


Detailed Description

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.

Author:
Josh Bloch
Version:
1.16, 12/03/01
See also:
Set

TreeSet

SortedMap

Collection

Comparable

Comparator

ClassCastException

Since:
1.2

Public Member Functions

virtual Ref< Comparatorcomparator () const =0
 Returns the comparator associated with this sorted set, or null if it uses its elements' natural ordering.
virtual Ref< SortedSetsubSet (const ObjectRef &fromElement, const ObjectRef &toElement) const =0
 Returns a view of the portion of this sorted set whose elements range from fromElement, inclusive, to toElement, exclusive.
virtual Ref< SortedSetheadSet (const ObjectRef &toElement) const =0
 Returns a view of the portion of this sorted set whose elements are strictly less than toElement.
virtual Ref< SortedSettailSet (const ObjectRef &fromElement) const =0
 Returns a view of the portion of this sorted set whose elements are greater than or equal to fromElement.
virtual ObjectRef first () const =0
 Returns the first (lowest) element currently in this sorted set.
virtual ObjectRef last () const =0
 Returns the last (highest) element currently in this sorted set.

Static Public Member Functions

static Ref< SortedSetsynchronizedSortedSet (const Ref< SortedSet > &c, const Ref< Sync > &sync=0)
 Returns a synchronized (thread-safe) sorted set backed by the specified sorted set.
static Ref< SortedSetimmutableSortedSet (const Ref< SortedSet > &c)
 Returns an unmodifiable view of the specified sorted set.

Member Function Documentation

static Ref<SortedSet> java::util::SortedSet::synchronizedSortedSet ( const Ref< SortedSet > &  c,
const Ref< Sync > &  sync = 0 
) [static]

Returns a synchronized (thread-safe) sorted set backed by the specified sorted set.

In order to guarantee serial access, it is critical that all access to the backing sorted set is accomplished through the returned sorted set (or its views).

It is imperative that the user manually synchronize on the returned sorted set when iterating over it or any of its subSet, headSet, or tailSet views.

  SortedSet s = Collections.synchronizedSortedSet(new HashSortedSet());
      ...
  synchronized(s) {
      Iterator i = s.iterator(); // Must be in the synchronized block
      while (i.hasNext())
          foo(i.next());
  }
 
or:
  SortedSet s = Collections.synchronizedSortedSet(new HashSortedSet());
  SortedSet s2 = s.headSet(foo);
      ...
  synchronized(s) {  // Note: s, not s2!!!
      Iterator i = s2.iterator(); // Must be in the synchronized block
      while (i.hasNext())
          foo(i.next());
  }
 
Failure to follow this advice may result in non-deterministic behavior.

The returned sorted set will be serializable if the specified sorted set is serializable.

Parameters:
s the sorted set to be "wrapped" in a synchronized sorted set.
Returns:
a synchronized view of the specified sorted set.

static Ref<SortedSet> java::util::SortedSet::immutableSortedSet ( const Ref< SortedSet > &  c  )  [static]

Returns an unmodifiable view of the specified sorted set.

This method allows modules to provide users with "read-only" access to internal sorted sets. Query operations on the returned sorted set "read through" to the specified sorted set. Attempts to modify the returned sorted set, whether direct, via its iterator, or via its subSet, headSet, or tailSet views, result in an UnsupportedOperationException.

The returned sorted set will be serializable if the specified sorted set is serializable.

Parameters:
s the sorted set for which an unmodifiable view is to be returned.
Returns:
an unmodifiable view of the specified sorted set.

virtual Ref<Comparator> java::util::SortedSet::comparator (  )  const [pure virtual]

Returns the comparator associated with this sorted set, or null if it uses its elements' natural ordering.

Returns:
the comparator associated with this sorted set, or null if it uses its elements' natural ordering.

Implemented in java::util::TreeSet.

virtual Ref<SortedSet> java::util::SortedSet::subSet ( const ObjectRef fromElement,
const ObjectRef toElement 
) const [pure virtual]

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+"");
 

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+"", high);
 

Parameters:
fromElement low endpoint (inclusive) of the subSet.
toElement high endpoint (exclusive) of the subSet.
Returns:
a view of the specified range within this sorted set.
Exceptions:
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.
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.
NullPointerException if fromElement or toElement is null and this sorted set does not tolerate null elements.

Implemented in java::util::TreeSet.

virtual Ref<SortedSet> java::util::SortedSet::headSet ( const ObjectRef toElement  )  const [pure virtual]

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+"");

Parameters:
toElement high endpoint (exclusive) of the headSet.
Returns:
a view of the specified initial range of this sorted set.
Exceptions:
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 sorted set does not tolerate null elements.
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.

Implemented in java::util::TreeSet.

virtual Ref<SortedSet> java::util::SortedSet::tailSet ( const ObjectRef fromElement  )  const [pure virtual]

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+"");

Parameters:
fromElement low endpoint (inclusive) of the tailSet.
Returns:
a view of the specified final range of this sorted set.
Exceptions:
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 sorted set does not tolerate null elements.
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.

Implemented in java::util::TreeSet.

virtual ObjectRef java::util::SortedSet::first (  )  const [pure virtual]

Returns the first (lowest) element currently in this sorted set.

Returns:
the first (lowest) element currently in this sorted set.
Exceptions:
NoSuchElementException sorted set is empty.

Implemented in java::util::TreeSet.

virtual ObjectRef java::util::SortedSet::last (  )  const [pure virtual]

Returns the last (highest) element currently in this sorted set.

Returns:
the last (highest) element currently in this sorted set.
Exceptions:
NoSuchElementException sorted set is empty.

Implemented in java::util::TreeSet.


The documentation for this class was generated from the following file:
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