Interface Predicate<T extends @Nullable java.lang.Object>
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- All Known Implementing Classes:
BloomFilter
,CharMatcher
,Range
@GwtCompatible public interface Predicate<T extends @Nullable java.lang.Object>
Determines a true or false value for a given input; a pre-Java-8 version ofjava.util.function.Predicate
.The
Predicates
class provides common predicates and related utilities.See the Guava User Guide article on the use of
Predicate
.For Java 8+ users
This interface is now a legacy type. Use
java.util.function.Predicate
(or the appropriate primitive specialization such asIntPredicate
) instead whenever possible. Otherwise, at least reduce explicit dependencies on this type by using lambda expressions or method references instead of classes, leaving your code easier to migrate in the future.To use a reference of this type (say, named
guavaPredicate
) in a context wherejava.util.function.Predicate
is expected, use the method referenceguavaPredicate::apply
. For the other direction, usejavaUtilPredicate::test
. A future version of this interface will be made to extendjava.util.function.Predicate
, so that conversion will be necessary in only one direction. At that time, this interface will be officially discouraged.- Since:
- 2.0
- Author:
- Kevin Bourrillion
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Method Summary
All Methods Instance Methods Abstract Methods Modifier and Type Method Description boolean
apply(T input)
Returns the result of applying this predicate toinput
(Java 8 users, see notes in the class documentation above).boolean
equals(java.lang.Object object)
Indicates whether another object is equal to this predicate.
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Method Detail
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apply
boolean apply(T input)
Returns the result of applying this predicate toinput
(Java 8 users, see notes in the class documentation above). This method is generally expected, but not absolutely required, to have the following properties:- Its execution does not cause any observable side effects.
- The computation is consistent with equals; that is,
Objects.equal
(a, b)
implies thatpredicate.apply(a) == predicate.apply(b))
.
- Throws:
java.lang.NullPointerException
- ifinput
is null and this predicate does not accept null arguments
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equals
boolean equals(@CheckForNull java.lang.Object object)
Indicates whether another object is equal to this predicate.Most implementations will have no reason to override the behavior of
Object.equals(java.lang.Object)
. However, an implementation may also choose to returntrue
wheneverobject
is aPredicate
that it considers interchangeable with this one. "Interchangeable" typically means thatthis.apply(t) == that.apply(t)
for allt
of typeT
). Note that afalse
result from this method does not imply that the predicates are known not to be interchangeable.- Overrides:
equals
in classjava.lang.Object
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