Class ForwardingSet<E extends @Nullable Object>
- java.lang.Object
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- com.google.common.collect.ForwardingObject
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- com.google.common.collect.ForwardingCollection<E>
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- com.google.common.collect.ForwardingSet<E>
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- All Implemented Interfaces:
Iterable<E>
,Collection<E>
,Set<E>
- Direct Known Subclasses:
ForwardingSortedSet
,TypeToken.TypeSet
@GwtCompatible public abstract class ForwardingSet<E extends @Nullable Object> extends ForwardingCollection<E> implements Set<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, overridingForwardingCollection.add(E)
alone will not change the behavior ofForwardingCollection.addAll(java.util.Collection<? extends E>)
, which can lead to unexpected behavior. In this case, you should overrideaddAll
as well, either providing your own implementation, or delegating to the providedstandardAddAll
method.default
method warning: This class does not forward calls todefault
methods. Instead, it inherits their default implementations. When those implementations invoke methods, they invoke methods on theForwardingSet
.The
standard
methods are not guaranteed to be thread-safe, even when all of the methods that they depend on are thread-safe.- Since:
- 2.0
- Author:
- Kevin Bourrillion, Louis Wasserman
-
-
Constructor Summary
Constructors Modifier Constructor Description protected
ForwardingSet()
Constructor for use by subclasses.
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Method Summary
All Methods Instance Methods Abstract Methods Concrete Methods Modifier and Type Method Description 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 ofequals(java.lang.Object)
in terms ofForwardingCollection.size()
andForwardingCollection.containsAll(java.util.Collection<?>)
.protected int
standardHashCode()
A sensible definition ofhashCode()
in terms ofForwardingCollection.iterator()
.protected boolean
standardRemoveAll(Collection<?> collection)
A sensible definition ofForwardingCollection.removeAll(java.util.Collection<?>)
in terms ofForwardingCollection.iterator()
andForwardingCollection.remove(java.lang.Object)
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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, standardRetainAll, standardToArray, standardToArray, standardToString, toArray, toArray
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Methods inherited from class com.google.common.collect.ForwardingObject
toString
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Methods inherited from class java.lang.Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait
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Methods inherited from interface java.util.Collection
parallelStream, removeIf, stream, toArray
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-
-
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Constructor Detail
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ForwardingSet
protected ForwardingSet()
Constructor for use by subclasses.
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Method Detail
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delegate
protected abstract Set<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 asdelegate()
. Concrete subclasses override this method to supply the instance being decorated.- Specified by:
delegate
in classForwardingCollection<E extends @Nullable Object>
-
equals
public boolean equals(@CheckForNull Object object)
Description copied from class:java.lang.Object
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.- Specified by:
equals
in interfaceCollection<E extends @Nullable Object>
- Specified by:
equals
in interfaceSet<E extends @Nullable Object>
- Overrides:
equals
in classObject
- Parameters:
object
- 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
-
hashCode
public int hashCode()
Description copied from class:java.lang.Object
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.)- Specified by:
hashCode
in interfaceCollection<E extends @Nullable Object>
- Specified by:
hashCode
in interfaceSet<E extends @Nullable Object>
- 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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standardRemoveAll
protected boolean standardRemoveAll(Collection<?> collection)
A sensible definition ofForwardingCollection.removeAll(java.util.Collection<?>)
in terms ofForwardingCollection.iterator()
andForwardingCollection.remove(java.lang.Object)
. If you overrideiterator
orremove
, you may wish to overrideForwardingCollection.removeAll(java.util.Collection<?>)
to forward to this implementation.- Overrides:
standardRemoveAll
in classForwardingCollection<E extends @Nullable Object>
- Since:
- 7.0 (this version overrides the
ForwardingCollection
version as of 12.0)
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standardEquals
protected boolean standardEquals(@CheckForNull Object object)
A sensible definition ofequals(java.lang.Object)
in terms ofForwardingCollection.size()
andForwardingCollection.containsAll(java.util.Collection<?>)
. If you override either of those methods, you may wish to overrideequals(java.lang.Object)
to forward to this implementation.- Since:
- 7.0
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standardHashCode
protected int standardHashCode()
A sensible definition ofhashCode()
in terms ofForwardingCollection.iterator()
. If you overrideForwardingCollection.iterator()
, you may wish to overrideequals(java.lang.Object)
to forward to this implementation.- Since:
- 7.0
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