Package com.google.common.collect

Class ForwardingNavigableSet<E>

java.lang.Object

com.google.common.collect.ForwardingObject

com.google.common.collect.ForwardingCollection<E>

com.google.common.collect.ForwardingSet<E>

com.google.common.collect.ForwardingSortedSet<E>

com.google.common.collect.ForwardingNavigableSet<E>

All Implemented Interfaces:

Iterable<E>, Collection<E>, NavigableSet<E>, Set<E>, SortedSet<E>

Direct Known Subclasses:

ForwardingNavigableSet.StandardDescendingSet

@GwtIncompatible
public abstract class ForwardingNavigableSet<E>
extends ForwardingSortedSet<E>
implements NavigableSet<E>

A navigable set which forwards all its method calls to another navigable set. Subclasses should override one or more methods to modify the behavior of the backing set as desired per the decorator pattern.

Warning: The methods of ForwardingNavigableSet forward indiscriminately to the methods of the delegate. For example, overriding ForwardingCollection.add(E) alone will not change the behavior of ForwardingCollection.addAll(java.util.Collection<? extends E>), which can lead to unexpected behavior. In this case, you should override addAll as well, either providing your own implementation, or delegating to the provided standardAddAll method.

default method warning: This class does not forward calls to default methods. Instead, it inherits their default implementations. When those implementations invoke methods, they invoke methods on the ForwardingNavigableSet.

Each of the standard methods uses the set's comparator (or the natural ordering of the elements, if there is no comparator) to test element equality. As a result, if the comparator is not consistent with equals, some of the standard implementations may violate the Set contract.

The standard methods and the collection views they return are not guaranteed to be thread-safe, even when all of the methods that they depend on are thread-safe.

Since:

12.0

Author:

Louis Wasserman

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
protected class	ForwardingNavigableSet.StandardDescendingSet	A sensible implementation of NavigableSet.descendingSet() in terms of the other methods of NavigableSet, notably including NavigableSet.descendingIterator().

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	ForwardingNavigableSet()	Constructor for use by subclasses.

Method Summary

Modifier and Type	Method	Description
E	ceiling(E e)	Returns the least element in this set greater than or equal to the given element, or null if there is no such element.
protected abstract NavigableSet<E>	delegate()	Returns the backing delegate instance that methods are forwarded to.
Iterator<E>	descendingIterator()	Returns an iterator over the elements in this set, in descending order.
NavigableSet<E>	descendingSet()	Returns a reverse order view of the elements contained in this set.
E	floor(E e)	Returns the greatest element in this set less than or equal to the given element, or null if there is no such element.
NavigableSet<E>	headSet(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.
E	higher(E e)	Returns the least element in this set strictly greater than the given element, or null if there is no such element.
E	lower(E e)	Returns the greatest element in this set strictly less than the given element, or null if there is no such element.
E	pollFirst()	Retrieves and removes the first (lowest) element, or returns null if this set is empty.
E	pollLast()	Retrieves and removes the last (highest) element, or returns null if this set is empty.
protected E	standardCeiling(E e)	A sensible definition of ceiling(E) in terms of the iterator method of tailSet(Object, boolean).
protected E	standardFirst()
protected E	standardFloor(E e)	A sensible definition of floor(E) in terms of the descendingIterator method of headSet(Object, boolean).
protected SortedSet<E>	standardHeadSet(E toElement)	A sensible definition of ForwardingSortedSet.headSet(Object) in terms of the headSet(Object, boolean) method.
protected E	standardHigher(E e)	A sensible definition of higher(E) in terms of the iterator method of tailSet(Object, boolean).
protected E	standardLast()
protected E	standardLower(E e)	A sensible definition of lower(E) in terms of the descendingIterator method of headSet(Object, boolean).
protected E	standardPollFirst()	A sensible definition of pollFirst() in terms of the iterator method.
protected E	standardPollLast()	A sensible definition of pollLast() in terms of the descendingIterator method.
protected NavigableSet<E>	standardSubSet(E fromElement, boolean fromInclusive, E toElement, boolean toInclusive)	A sensible definition of subSet(Object, boolean, Object, boolean) in terms of the headSet and tailSet methods.
protected SortedSet<E>	standardSubSet(E fromElement, E toElement)	A sensible definition of ForwardingSortedSet.subSet(Object, Object) in terms of the subSet(Object, boolean, Object, boolean) method.
protected SortedSet<E>	standardTailSet(E fromElement)	A sensible definition of ForwardingSortedSet.tailSet(Object) in terms of the tailSet(Object, boolean) method.
NavigableSet<E>	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.
NavigableSet<E>	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.

Methods inherited from class com.google.common.collect.ForwardingSortedSet

comparator, first, headSet, last, standardContains, standardRemove, subSet, tailSet

Methods inherited from class com.google.common.collect.ForwardingSet

equals, hashCode, standardEquals, standardHashCode, standardRemoveAll

Methods inherited from class com.google.common.collect.ForwardingCollection

add, addAll, clear, contains, containsAll, isEmpty, iterator, remove, removeAll, retainAll, size, standardAddAll, standardClear, standardContainsAll, standardIsEmpty, standardRetainAll, standardToArray, standardToArray, standardToString, toArray, toArray

Methods inherited from class com.google.common.collect.ForwardingObject

toString

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.Collection

parallelStream, removeIf, stream, toArray

Methods inherited from interface java.lang.Iterable

forEach

Methods inherited from interface java.util.NavigableSet

headSet, iterator, subSet, tailSet

Methods inherited from interface java.util.Set

add, addAll, clear, contains, containsAll, equals, hashCode, isEmpty, remove, removeAll, retainAll, size, toArray, toArray

Methods inherited from interface java.util.SortedSet

comparator, first, last, spliterator

Constructor Detail

ForwardingNavigableSet

protected ForwardingNavigableSet()

Constructor for use by subclasses.

Method Detail

delegate

protected abstract NavigableSet<E> delegate()

Description copied from class: ForwardingObject

Returns the backing delegate instance that methods are forwarded to. Abstract subclasses generally override this method with an abstract method that has a more specific return type, such as ForwardingSet.delegate(). Concrete subclasses override this method to supply the instance being decorated.

Specified by:

delegate in class ForwardingSortedSet<E>

lower

public E lower(E e)

Description copied from interface: java.util.NavigableSet

Returns the greatest element in this set strictly less than the given element, or null if there is no such element.

Specified by:

lower in interface NavigableSet<E>

Parameters:

e - the value to match

Returns:

the greatest element less than e, or null if there is no such element

standardLower

protected E standardLower(E e)

A sensible definition of lower(E) in terms of the descendingIterator method of headSet(Object, boolean). If you override headSet(Object, boolean), you may wish to override lower(E) to forward to this implementation.

floor

public E floor(E e)

Description copied from interface: java.util.NavigableSet

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:

floor in interface NavigableSet<E>

Parameters:

e - the value to match

Returns:

the greatest element less than or equal to e, or null if there is no such element

standardFloor

protected E standardFloor(E e)

A sensible definition of floor(E) in terms of the descendingIterator method of headSet(Object, boolean). If you override headSet(Object, boolean), you may wish to override floor(E) to forward to this implementation.

ceiling

public E ceiling(E e)

Description copied from interface: java.util.NavigableSet

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:

ceiling in interface NavigableSet<E>

Parameters:

e - the value to match

Returns:

the least element greater than or equal to e, or null if there is no such element

standardCeiling

protected E standardCeiling(E e)

A sensible definition of ceiling(E) in terms of the iterator method of tailSet(Object, boolean). If you override tailSet(Object, boolean), you may wish to override ceiling(E) to forward to this implementation.

higher

public E higher(E e)

Description copied from interface: java.util.NavigableSet

Returns the least element in this set strictly greater than the given element, or null if there is no such element.

Specified by:

higher in interface NavigableSet<E>

Parameters:

e - the value to match

Returns:

the least element greater than e, or null if there is no such element

standardHigher

protected E standardHigher(E e)

A sensible definition of higher(E) in terms of the iterator method of tailSet(Object, boolean). If you override tailSet(Object, boolean), you may wish to override higher(E) to forward to this implementation.

pollFirst

public E pollFirst()

Description copied from interface: java.util.NavigableSet

Retrieves and removes the first (lowest) element, or returns null if this set is empty.

Specified by:

pollFirst in interface NavigableSet<E>

Returns:

the first element, or null if this set is empty

standardPollFirst

protected E standardPollFirst()

A sensible definition of pollFirst() in terms of the iterator method. If you override ForwardingCollection.iterator() you may wish to override pollFirst() to forward to this implementation.

pollLast

public E pollLast()

Description copied from interface: java.util.NavigableSet

Retrieves and removes the last (highest) element, or returns null if this set is empty.

Specified by:

pollLast in interface NavigableSet<E>

Returns:

the last element, or null if this set is empty

standardPollLast

protected E standardPollLast()

A sensible definition of pollLast() in terms of the descendingIterator method. If you override descendingIterator() you may wish to override pollLast() to forward to this implementation.

standardFirst

protected E standardFirst()

standardLast

protected E standardLast()

descendingSet

public NavigableSet<E> descendingSet()

Description copied from interface: java.util.NavigableSet

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:

descendingSet in interface NavigableSet<E>

Returns:

a reverse order view of this set

descendingIterator

public Iterator<E> descendingIterator()

Description copied from interface: java.util.NavigableSet

Returns an iterator over the elements in this set, in descending order. Equivalent in effect to descendingSet().iterator().

Specified by:

descendingIterator in interface NavigableSet<E>

Returns:

an iterator over the elements in this set, in descending order

subSet

public NavigableSet<E> subSet(E fromElement,
                              boolean fromInclusive,
                              E toElement,
                              boolean toInclusive)

Description copied from interface: java.util.NavigableSet

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:

subSet in interface NavigableSet<E>

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

standardSubSet

@Beta
protected NavigableSet<E> standardSubSet(E fromElement,
                                         boolean fromInclusive,
                                         E toElement,
                                         boolean toInclusive)

A sensible definition of subSet(Object, boolean, Object, boolean) in terms of the headSet and tailSet methods. In many cases, you may wish to override subSet(Object, boolean, Object, boolean) to forward to this implementation.

standardSubSet

protected SortedSet<E> standardSubSet(E fromElement,
                                      E toElement)

A sensible definition of ForwardingSortedSet.subSet(Object, Object) in terms of the subSet(Object, boolean, Object, boolean) method. If you override subSet(Object, boolean, Object, boolean), you may wish to override ForwardingSortedSet.subSet(Object, Object) to forward to this implementation.

Overrides:

standardSubSet in class ForwardingSortedSet<E>

headSet

public NavigableSet<E> headSet(E toElement,
                               boolean inclusive)

Description copied from interface: java.util.NavigableSet

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:

headSet in interface NavigableSet<E>

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

standardHeadSet

protected SortedSet<E> standardHeadSet(E toElement)

A sensible definition of ForwardingSortedSet.headSet(Object) in terms of the headSet(Object, boolean) method. If you override headSet(Object, boolean), you may wish to override ForwardingSortedSet.headSet(Object) to forward to this implementation.

tailSet

public NavigableSet<E> tailSet(E fromElement,
                               boolean inclusive)

Description copied from interface: java.util.NavigableSet

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:

tailSet in interface NavigableSet<E>

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

standardTailSet

protected SortedSet<E> standardTailSet(E fromElement)

A sensible definition of ForwardingSortedSet.tailSet(Object) in terms of the tailSet(Object, boolean) method. If you override tailSet(Object, boolean), you may wish to override ForwardingSortedSet.tailSet(Object) to forward to this implementation.