Interface Multiset.Entry<E extends @Nullable Object>
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public static interface Multiset.Entry<E extends @Nullable Object>
An unmodifiable element-count pair for a multiset. TheMultiset.entrySet()
method returns a view of the multiset whose elements are of this class. A multiset implementation may return Entry instances that are either live "read-through" views to the Multiset, or immutable snapshots. Note that this type is unrelated to the similarly-named typeMap.Entry
.- Since:
- 2.0
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Method Summary
All Methods Instance Methods Abstract Methods Modifier and Type Method Description boolean
equals(Object o)
Indicates whether some other object is "equal to" this one.int
getCount()
Returns the count of the associated element in the underlying multiset.E
getElement()
Returns the multiset element corresponding to this entry.int
hashCode()
Returns a hash code value for the object.String
toString()
Returns the canonical string representation of this entry, defined as follows.
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Method Detail
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getElement
E getElement()
Returns the multiset element corresponding to this entry. Multiple calls to this method always return the same instance.- Returns:
- the element corresponding to this entry
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getCount
int getCount()
Returns the count of the associated element in the underlying multiset. This count may either be an unchanging snapshot of the count at the time the entry was retrieved, or a live view of the current count of the element in the multiset, depending on the implementation. Note that in the former case, this method can never return zero, while in the latter, it will return zero if all occurrences of the element were since removed from the multiset.- Returns:
- the count of the element; never negative
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equals
boolean equals(@CheckForNull Object o)
Indicates whether some other object is "equal to" this one.The
equals
method implements an equivalence relation on non-null object references:- It is reflexive: for any non-null reference value
x
,x.equals(x)
should returntrue
. - It is symmetric: for any non-null reference values
x
andy
,x.equals(y)
should returntrue
if and only ify.equals(x)
returnstrue
. - It is transitive: for any non-null reference values
x
,y
, andz
, ifx.equals(y)
returnstrue
andy.equals(z)
returnstrue
, thenx.equals(z)
should returntrue
. - It is consistent: for any non-null reference values
x
andy
, multiple invocations ofx.equals(y)
consistently returntrue
or consistently returnfalse
, provided no information used inequals
comparisons on the objects is modified. - For any non-null reference value
x
,x.equals(null)
should returnfalse
.
The
equals
method for classObject
implements the most discriminating possible equivalence relation on objects; that is, for any non-null reference valuesx
andy
, this method returnstrue
if and only ifx
andy
refer to the same object (x == y
has the valuetrue
).Note that it is generally necessary to override the
hashCode
method whenever this method is overridden, so as to maintain the general contract for thehashCode
method, which states that equal objects must have equal hash codes.Returns
true
if the given object is also a multiset entry and the two entries represent the same element and count. That is, two entriesa
andb
are equal if:Objects.equal(a.getElement(), b.getElement()) && a.getCount() == b.getCount()
- Overrides:
equals
in classObject
- Parameters:
o
- the reference object with which to compare.- Returns:
true
if this object is the same as the obj argument;false
otherwise.- See Also:
Object.hashCode()
,HashMap
- It is reflexive: for any non-null reference value
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hashCode
int hashCode()
Returns a hash code value for the object. This method is supported for the benefit of hash tables such as those provided byHashMap
.The general contract of
hashCode
is:- Whenever it is invoked on the same object more than once during
an execution of a Java application, the
hashCode
method must consistently return the same integer, provided no information used inequals
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. - If two objects are equal according to the
equals(Object)
method, then calling thehashCode
method on each of the two objects must produce the same integer result. - It is not required that if two objects are unequal
according to the
Object.equals(java.lang.Object)
method, then calling thehashCode
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. (The hashCode may or may not be implemented as some function of an object's memory address at some point in time.)The hash code of a multiset entry for element
element
and countcount
is defined as:((element == null) ? 0 : element.hashCode()) ^ count
- Overrides:
hashCode
in classObject
- Returns:
- a hash code value for this object.
- See Also:
Object.equals(java.lang.Object)
,System.identityHashCode(java.lang.Object)
- Whenever it is invoked on the same object more than once during
an execution of a Java application, the
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toString
String toString()
Returns the canonical string representation of this entry, defined as follows. If the count for this entry is one, this is simply the string representation of the corresponding element. Otherwise, it is the string representation of the element, followed by the three characters" x "
(space, letter x, space), followed by the count.
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