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java.lang.Objectcom.google.common.collect.ForwardingObject
com.google.common.collect.ForwardingCollection<E>
com.google.common.collect.ForwardingMultiset<E>
public abstract class ForwardingMultiset<E>
A multiset which forwards all its method calls to another multiset. Subclasses should override one or more methods to modify the behavior of the backing multiset as desired per the decorator pattern.
ForwardingObject
,
Serialized FormNested Class Summary |
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Nested classes/interfaces inherited from interface com.google.common.collect.Multiset |
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Multiset.Entry<E> |
Constructor Summary | |
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protected |
ForwardingMultiset(Multiset<E> delegate)
Constructs a forwarding multiset that forwards to the provided delegate. |
Method Summary | |
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boolean |
add(E element,
int occurrences)
Adds a number of occurrences of an element to this multiset. |
int |
count(Object element)
Returns the number of occurrences of an element in this multiset (the count of the element). |
protected Multiset<E> |
delegate()
Returns the backing delegate object. |
Set<E> |
elementSet()
Returns the set of distinct elements contained in this multiset. |
Set<Multiset.Entry<E>> |
entrySet()
Returns a view of the contents of this multiset, grouped into Multiset.Entry instances, each providing an element of the multiset and
the count of that element. |
boolean |
equals(Object obj)
Compares the specified object with this multiset for equality. |
int |
hashCode()
Returns the hash code for this multiset. |
int |
remove(Object element,
int occurrences)
Conditionally removes a number of occurrences of an element from this multiset, provided that at least this many occurrences are present. |
int |
removeAllOccurrences(Object element)
Removes all occurrences of the specified element from this multiset. |
Methods inherited from class com.google.common.collect.ForwardingCollection |
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add, addAll, clear, contains, containsAll, containsAllImpl, containsImpl, isEmpty, iterator, remove, removeAll, removeAllImpl, removeImpl, retainAll, retainAllImpl, size, toArray, toArray, toArrayImpl, toArrayImpl, toStringImpl |
Methods inherited from class com.google.common.collect.ForwardingObject |
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toString |
Methods inherited from class java.lang.Object |
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clone, finalize, getClass, notify, notifyAll, toString, wait, wait, wait |
Methods inherited from interface com.google.common.collect.Multiset |
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add, contains, containsAll, remove, removeAll, retainAll, toString |
Methods inherited from interface java.util.Collection |
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addAll, clear, isEmpty, iterator, size, toArray, toArray |
Constructor Detail |
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protected ForwardingMultiset(Multiset<E> delegate)
Method Detail |
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protected Multiset<E> delegate()
ForwardingObject
@SuppressWarnings("unchecked") @Override protected Foo delegate() { return (Foo) super.delegate(); }This method should always return the same delegate instance that was passed to the constructor.
delegate
in class ForwardingCollection<E>
public int count(Object element)
Multiset
Object.equals(java.lang.Object)
-based
multiset, this gives the same result as Collections.frequency(java.util.Collection>, java.lang.Object)
(which would presumably perform more poorly).
Note: the utility method Iterables.frequency(java.lang.Iterable>, java.lang.Object)
generalizes
this operation; it correctly delegates to this method when dealing with a
multiset, but it can also accept any other iterable type.
count
in interface Multiset<E>
element
- the element to count occurrences of
public boolean add(E element, int occurrences)
Multiset
occurrences == 1
, this method has the identical effect to Multiset.add(Object)
. This method is functionally equivalent (except in the case
of overflow) to the call addAll(Collections.nCopies(element,
occurrences))
, which would presumably perform much more poorly.
add
in interface Multiset<E>
element
- the element to add occurrences of; may be null
only
if explicitly allowed by the implementationoccurrences
- the number of occurrences of this element to add. May
be zero, in which case no change will be made.
public int remove(Object element, int occurrences)
Multiset
occurrences
, no change is made.
Note that if
occurrences == 1
, this is functionally equivalent to the call
remove(element)
.
remove
in interface Multiset<E>
element
- the element to conditionally remove occurrences ofoccurrences
- the number of occurrences of this element to remove. May
be zero, in which case no change will be made.
true
if the condition for modification was met. Unless
occurrences
is zero, this implies that the multiset was indeed
modified.public int removeAllOccurrences(Object element)
Multiset
Multiset.remove(Object)
, which removes only
one occurrence at a time.
TODO: Nuke this. Use setCount(e, 0).
removeAllOccurrences
in interface Multiset<E>
element
- the element whose occurrences should all be removed
public Set<E> elementSet()
Multiset
If the element set supports any removal operations, these necessarily cause all occurrences of the removed element(s) to be removed from the multiset. Implementations are not expected to support the add operations, although this is possible.
A common use for the element set is to find the number of distinct
elements in the multiset: elementSet().size()
.
elementSet
in interface Multiset<E>
public Set<Multiset.Entry<E>> entrySet()
Multiset
Multiset.Entry
instances, each providing an element of the multiset and
the count of that element. This set contains exactly one entry for each
distinct element in the multiset (thus it always has the same size as the
Multiset.elementSet()
). The order of the elements in the element set is
unspecified.
The entry set is backed by the same data as the multiset, so any change
to either is immediately reflected in the other. However, multiset changes
may or may not be reflected in any Entry
instances already
retrieved from the entry set (this is implementation-dependent).
Furthermore, implementations are not required to support modifications to
the entry set at all, and the Entry
instances themselves don't
even have methods for modification. See the specific implementation class
for more details on how its entry set handles modifications.
entrySet
in interface Multiset<E>
public boolean equals(Object obj)
Multiset
true
if the given object is also a multiset and contains equal
elements with equal counts, regardless of order.
TODO: caveats about equivalence-relation.
equals
in interface Multiset<E>
equals
in interface Collection<E>
equals
in class Object
public int hashCode()
Multiset
(element == null ? 0 : element.hashCode()) ^ count(element)over all distinct elements in the multiset. It follows that a multiset and its entry set always have the same hash code.
hashCode
in interface Multiset<E>
hashCode
in interface Collection<E>
hashCode
in class Object
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