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java.lang.Object com.google.common.collect.ForwardingObject com.google.common.collect.ForwardingCollection<E> com.google.common.collect.ForwardingSet<E>
@GwtCompatible public abstract class ForwardingSet<E>
A set which forwards all its method calls to another 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 ForwardingSet
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.
The standard
methods are not guaranteed to be thread-safe, even
when all of the methods that they depend on are thread-safe.
Constructor Summary | |
---|---|
protected |
ForwardingSet()
Constructor for use by subclasses. |
Method Summary | |
---|---|
protected abstract Set<E> |
delegate()
Returns the backing delegate instance that methods are forwarded to. |
boolean |
equals(Object object)
Indicates whether some other object is "equal to" this one. |
int |
hashCode()
Returns a hash code value for the object. |
protected boolean |
standardEquals(Object object)
A sensible definition of equals(java.lang.Object) in terms of ForwardingCollection.size() and
ForwardingCollection.containsAll(java.util.Collection>) . |
protected int |
standardHashCode()
A sensible definition of hashCode() in terms of ForwardingCollection.iterator() . |
Methods inherited from class com.google.common.collect.ForwardingCollection |
---|
add, addAll, clear, contains, containsAll, isEmpty, iterator, remove, removeAll, retainAll, size, standardAddAll, standardClear, standardContains, standardContainsAll, standardIsEmpty, standardRemove, standardRemoveAll, 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.Set |
---|
add, addAll, clear, contains, containsAll, isEmpty, iterator, remove, removeAll, retainAll, size, toArray, toArray |
Constructor Detail |
---|
protected ForwardingSet()
Method Detail |
---|
protected abstract Set<E> delegate()
ForwardingObject
delegate()
. Concrete subclasses override this method to supply
the instance being decorated.
delegate
in class ForwardingCollection<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 Collection<E>
equals
in interface Set<E>
equals
in class Object
object
- the reference object with which to compare.
true
if this object is the same as the obj
argument; false
otherwise.Object.hashCode()
,
Hashtable
public int hashCode()
java.lang.Object
java.util.Hashtable
.
The general contract of hashCode
is:
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 hashtables.
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 Collection<E>
hashCode
in interface Set<E>
hashCode
in class Object
Object.equals(java.lang.Object)
,
Hashtable
@Beta protected boolean standardEquals(@Nullable Object object)
equals(java.lang.Object)
in terms of ForwardingCollection.size()
and
ForwardingCollection.containsAll(java.util.Collection>)
. If you override either of those methods, you may wish
to override equals(java.lang.Object)
to forward to this implementation.
@Beta protected int standardHashCode()
hashCode()
in terms of ForwardingCollection.iterator()
.
If you override ForwardingCollection.iterator()
, you may wish to override equals(java.lang.Object)
to forward to this implementation.
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