com.google.common.collect.ForwardingObject
com.google.common.collect.ForwardingCollection<E>
com.google.common.collect.ForwardingMultiset<E>
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java.lang.Object
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.
| Nested Class Summary |
|---|
| Nested classes/interfaces inherited from interface com.google.common.collect.Multiset |
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Multiset.Entry<E> |
| Constructor Summary | |
|---|---|
protected |
ForwardingMultiset()
Constructor for use by subclasses. |
| Method Summary | |
|---|---|
int |
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 abstract Multiset<E> |
delegate()
Returns the backing delegate instance that methods are forwarded to. |
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 object)
Indicates whether some other object is "equal to" this one. |
int |
hashCode()
Returns a hash code value for the object. |
int |
remove(Object element,
int occurrences)
Removes a number of occurrences of the specified element from this multiset. |
int |
setCount(E element,
int count)
Adds or removes the necessary occurrences of an element such that the element attains the desired count. |
boolean |
setCount(E element,
int oldCount,
int newCount)
Conditionally sets the count of an element to a new value, as described in Multiset.setCount(Object, int), provided that the element has the expected
current count. |
| Methods inherited from class com.google.common.collect.ForwardingCollection |
|---|
add, addAll, clear, contains, containsAll, isEmpty, iterator, remove, removeAll, retainAll, size, toArray, toArray |
| 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, wait, wait, wait |
| Methods inherited from interface com.google.common.collect.Multiset |
|---|
add, contains, containsAll, iterator, remove, removeAll, retainAll, toString |
| Methods inherited from interface java.util.Collection |
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addAll, clear, isEmpty, size, toArray, toArray |
| Constructor Detail |
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protected ForwardingMultiset()
| Method Detail |
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protected abstract Multiset<E> delegate()
ForwardingObjectForwardingSet.delegate(). Concrete subclasses override this method to supply
the instance being decorated.
delegate in class ForwardingCollection<E>public int count(Object element)
MultisetObject.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 int add(E element,
int occurrences)
Multisetoccurrences == 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 the element to add. May be
zero, in which case no change will be made.
public int remove(Object element,
int occurrences)
Multisetoccurrences == 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 the element to remove. May
be zero, in which case no change will be made.
public Set<E> elementSet()
MultisetIf 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()
MultisetMultiset.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(@Nullable
Object object)
java.lang.Object
The equals method implements an equivalence relation
on non-null object references:
x, x.equals(x) should return
true.
x and y, x.equals(y)
should return true if and only if
y.equals(x) returns true.
x, y, and z, if
x.equals(y) returns true and
y.equals(z) returns true, then
x.equals(z) should return true.
x and y, multiple invocations of
x.equals(y) consistently return true
or consistently return false, provided no
information used in equals comparisons on the
objects is modified.
x,
x.equals(null) should return false.
The equals method for class Object implements
the most discriminating possible equivalence relation on objects;
that is, for any non-null reference values x and
y, this method returns true if and only
if x and y refer to the same object
(x == y has the value true).
Note that it is generally necessary to override the hashCode
method whenever this method is overridden, so as to maintain the
general contract for the hashCode method, which states
that equal objects must have equal hash codes.
equals in interface Multiset<E>equals in interface Collection<E>equals in class Objectobject - the reference object with which to compare.
true if this object is the same as the obj
argument; false otherwise.Object.hashCode(),
HashMappublic int hashCode()
java.lang.ObjectHashMap.
The general contract of hashCode is:
hashCode method
must consistently return the same integer, provided no information
used in equals comparisons on the object is modified.
This integer need not remain consistent from one execution of an
application to another execution of the same application.
equals(Object)
method, then calling the hashCode method on each of
the two objects must produce the same integer result.
Object.equals(java.lang.Object)
method, then calling the hashCode method on each of the
two objects must produce distinct integer results. However, the
programmer should be aware that producing distinct integer results
for unequal objects may improve the performance of hash tables.
As much as is reasonably practical, the hashCode method defined by
class Object does return distinct integers for distinct
objects. (This is typically implemented by converting the internal
address of the object into an integer, but this implementation
technique is not required by the
JavaTM programming language.)
hashCode in interface Multiset<E>hashCode in interface Collection<E>hashCode in class ObjectObject.equals(java.lang.Object),
System.identityHashCode(java.lang.Object)
public int setCount(E element,
int count)
Multiset
setCount in interface Multiset<E>element - the element to add or remove occurrences of; may be null
only if explicitly allowed by the implementationcount - the desired count of the element in this multiset
public boolean setCount(E element,
int oldCount,
int newCount)
MultisetMultiset.setCount(Object, int), provided that the element has the expected
current count. If the current count is not oldCount, no change is
made.
setCount in interface Multiset<E>element - the element to conditionally set the count of; may be null
only if explicitly allowed by the implementationoldCount - the expected present count of the element in this multisetnewCount - the desired count of the element in this multiset
true if the condition for modification was met. This
implies that the multiset was indeed modified, unless
oldCount == newCount.
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