Class PredicateUtils
java.lang.Object
org.apache.commons.collections4.PredicateUtils
PredicateUtils provides reference implementations and utilities
 for the Predicate functor interface. The supplied predicates are:
 - Invoker - returns the result of a method call on the input object
- InstanceOf - true if the object is an instanceof a class
- Equal - true if the object equals() a specified object
- Identity - true if the object == a specified object
- Null - true if the object is null
- NotNull - true if the object is not null
- Unique - true if the object has not already been evaluated
- And/All - true if all of the predicates are true
- Or/Any - true if any of the predicates is true
- Either/One - true if only one of the predicate is true
- Neither/None - true if none of the predicates are true
- Not - true if the predicate is false, and vice versa
- Transformer - wraps a Transformer as a Predicate
- True - always return true
- False - always return false
- Exception - always throws an exception
- NullIsException/NullIsFalse/NullIsTrue - check for null input
- Transformed - transforms the input before calling the predicate
All the supplied predicates are Serializable.
- Since:
- 3.0
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Method SummaryModifier and TypeMethodDescriptionstatic <T> Predicate<T> allPredicate(Collection<? extends Predicate<? super T>> predicates) Create a new Predicate that returns true only if all of the specified predicates are true.static <T> Predicate<T> allPredicate(Predicate<? super T>... predicates) Create a new Predicate that returns true only if all of the specified predicates are true.static <T> Predicate<T> andPredicate(Predicate<? super T> predicate1, Predicate<? super T> predicate2) Create a new Predicate that returns true only if both of the specified predicates are true.static <T> Predicate<T> anyPredicate(Collection<? extends Predicate<? super T>> predicates) Create a new Predicate that returns true if any of the specified predicates are true.static <T> Predicate<T> anyPredicate(Predicate<? super T>... predicates) Create a new Predicate that returns true if any of the specified predicates are true.static <T> Predicate<T> asPredicate(Transformer<? super T, Boolean> transformer) Create a new Predicate that wraps a Transformer.static <T> Predicate<T> eitherPredicate(Predicate<? super T> predicate1, Predicate<? super T> predicate2) Create a new Predicate that returns true if one, but not both, of the specified predicates are true.static <T> Predicate<T> equalPredicate(T value) Creates a Predicate that checks if the input object is equal to the specified object using equals().static <T> Predicate<T> Gets a Predicate that always throws an exception.static <T> Predicate<T> Gets a Predicate that always returns false.static <T> Predicate<T> identityPredicate(T value) Creates a Predicate that checks if the input object is equal to the specified object by identity.instanceofPredicate(Class<?> type) Creates a Predicate that checks if the object passed in is of a particular type, using instanceof.static <T> Predicate<T> invokerPredicate(String methodName) Creates a Predicate that invokes a method on the input object.static <T> Predicate<T> invokerPredicate(String methodName, Class<?>[] paramTypes, Object[] args) Creates a Predicate that invokes a method on the input object.static <T> Predicate<T> neitherPredicate(Predicate<? super T> predicate1, Predicate<? super T> predicate2) Create a new Predicate that returns true if neither of the specified predicates are true.static <T> Predicate<T> nonePredicate(Collection<? extends Predicate<? super T>> predicates) Create a new Predicate that returns true if none of the specified predicates are true.static <T> Predicate<T> nonePredicate(Predicate<? super T>... predicates) Create a new Predicate that returns true if none of the specified predicates are true.static <T> Predicate<T> Gets a Predicate that checks if the input object passed in is not null.static <T> Predicate<T> notPredicate(Predicate<? super T> predicate) Create a new Predicate that returns true if the specified predicate returns false and vice versa.static <T> Predicate<T> nullIsExceptionPredicate(Predicate<? super T> predicate) Gets a Predicate that throws an exception if the input object is null, otherwise it calls the specified Predicate.static <T> Predicate<T> nullIsFalsePredicate(Predicate<? super T> predicate) Gets a Predicate that returns false if the input object is null, otherwise it calls the specified Predicate.static <T> Predicate<T> nullIsTruePredicate(Predicate<? super T> predicate) Gets a Predicate that returns true if the input object is null, otherwise it calls the specified Predicate.static <T> Predicate<T> Gets a Predicate that checks if the input object passed in is null.static <T> Predicate<T> onePredicate(Collection<? extends Predicate<? super T>> predicates) Create a new Predicate that returns true if only one of the specified predicates are true.static <T> Predicate<T> onePredicate(Predicate<? super T>... predicates) Create a new Predicate that returns true if only one of the specified predicates are true.static <T> Predicate<T> orPredicate(Predicate<? super T> predicate1, Predicate<? super T> predicate2) Create a new Predicate that returns true if either of the specified predicates are true.static <T> Predicate<T> transformedPredicate(Transformer<? super T, ? extends T> transformer, Predicate<? super T> predicate) Creates a predicate that transforms the input object before passing it to the predicate.static <T> Predicate<T> Gets a Predicate that always returns true.static <T> Predicate<T> Creates a Predicate that returns true the first time an object is encountered, and false if the same object is received again.
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Method Details- 
allPredicateCreate a new Predicate that returns true only if all of the specified predicates are true. The predicates are checked in iterator order. If the collection of predicates is empty, then this predicate returns true.- Type Parameters:
- T- the type that the predicate queries
- Parameters:
- predicates- a collection of predicates to check, may not be null
- Returns:
- the allpredicate
- Throws:
- NullPointerException- if the predicates collection is null
- NullPointerException- if any predicate in the collection is null
- See Also:
 
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allPredicateCreate a new Predicate that returns true only if all of the specified predicates are true. If the array of predicates is empty, then this predicate returns true.- Type Parameters:
- T- the type that the predicate queries
- Parameters:
- predicates- an array of predicates to check, may not be null
- Returns:
- the allpredicate
- Throws:
- NullPointerException- if the predicates array is null
- NullPointerException- if any predicate in the array is null
- See Also:
 
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andPredicatepublic static <T> Predicate<T> andPredicate(Predicate<? super T> predicate1, Predicate<? super T> predicate2) Create a new Predicate that returns true only if both of the specified predicates are true.- Type Parameters:
- T- the type that the predicate queries
- Parameters:
- predicate1- the first predicate, may not be null
- predicate2- the second predicate, may not be null
- Returns:
- the andpredicate
- Throws:
- NullPointerException- if either predicate is null
- See Also:
 
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anyPredicateCreate a new Predicate that returns true if any of the specified predicates are true. The predicates are checked in iterator order. If the collection of predicates is empty, then this predicate returns false.- Type Parameters:
- T- the type that the predicate queries
- Parameters:
- predicates- a collection of predicates to check, may not be null
- Returns:
- the anypredicate
- Throws:
- NullPointerException- if the predicates collection is null
- NullPointerException- if any predicate in the collection is null
- See Also:
 
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anyPredicateCreate a new Predicate that returns true if any of the specified predicates are true. If the array of predicates is empty, then this predicate returns false.- Type Parameters:
- T- the type that the predicate queries
- Parameters:
- predicates- an array of predicates to check, may not be null
- Returns:
- the anypredicate
- Throws:
- NullPointerException- if the predicates array is null
- NullPointerException- if any predicate in the array is null
- See Also:
 
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asPredicateCreate a new Predicate that wraps a Transformer. The Transformer must return eitherBoolean.TRUEorBoolean.FALSEotherwise a PredicateException will be thrown.- Type Parameters:
- T- the type that the predicate queries
- Parameters:
- transformer- the transformer to wrap, may not be null
- Returns:
- the transformer wrapping predicate
- Throws:
- NullPointerException- if the transformer is null
- See Also:
 
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eitherPredicatepublic static <T> Predicate<T> eitherPredicate(Predicate<? super T> predicate1, Predicate<? super T> predicate2) Create a new Predicate that returns true if one, but not both, of the specified predicates are true. XOR- Type Parameters:
- T- the type that the predicate queries
- Parameters:
- predicate1- the first predicate, may not be null
- predicate2- the second predicate, may not be null
- Returns:
- the eitherpredicate
- Throws:
- NullPointerException- if either predicate is null
- See Also:
 
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equalPredicateCreates a Predicate that checks if the input object is equal to the specified object using equals().- Type Parameters:
- T- the type that the predicate queries
- Parameters:
- value- the value to compare against
- Returns:
- the predicate
- See Also:
 
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exceptionPredicateGets a Predicate that always throws an exception. This could be useful during testing as a placeholder.- Type Parameters:
- T- the type that the predicate queries
- Returns:
- the predicate
- See Also:
 
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falsePredicateGets a Predicate that always returns false.- Type Parameters:
- T- the type that the predicate queries
- Returns:
- the predicate
- See Also:
 
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identityPredicateCreates a Predicate that checks if the input object is equal to the specified object by identity.- Type Parameters:
- T- the type that the predicate queries
- Parameters:
- value- the value to compare against
- Returns:
- the predicate
- See Also:
 
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instanceofPredicateCreates a Predicate that checks if the object passed in is of a particular type, using instanceof. Anullinput object will returnfalse.- Parameters:
- type- the type to check for, may not be null
- Returns:
- the predicate
- Throws:
- NullPointerException- if the class is null
- See Also:
 
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invokerPredicateCreates a Predicate that invokes a method on the input object. The method must return either a boolean or a non-null Boolean, and have no parameters. If the input object is null, a PredicateException is thrown.For ePredicateUtils.invokerPredicate("isEmpty");} will call the isEmptymethod on the input object to determine the predicate result.- Type Parameters:
- T- the type that the predicate queries
- Parameters:
- methodName- the method name to call on the input object, may not be null
- Returns:
- the predicate
- Throws:
- NullPointerException- if the methodName is null.
- See Also:
 
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invokerPredicatepublic static <T> Predicate<T> invokerPredicate(String methodName, Class<?>[] paramTypes, Object[] args) Creates a Predicate that invokes a method on the input object. The method must return either a boolean or a non-null Boolean, and have no parameters. If the input object is null, a PredicateException is thrown.For example, PredicateUtils.invokerPredicate("isEmpty");will call theisEmptymethod on the input object to determine the predicate result.- Type Parameters:
- T- the type that the predicate queries
- Parameters:
- methodName- the method name to call on the input object, may not be null
- paramTypes- the parameter types
- args- the arguments
- Returns:
- the predicate
- Throws:
- NullPointerException- if the method name is null
- IllegalArgumentException- if the paramTypes and args don't match
- See Also:
 
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neitherPredicatepublic static <T> Predicate<T> neitherPredicate(Predicate<? super T> predicate1, Predicate<? super T> predicate2) Create a new Predicate that returns true if neither of the specified predicates are true.- Type Parameters:
- T- the type that the predicate queries
- Parameters:
- predicate1- the first predicate, may not be null
- predicate2- the second predicate, may not be null
- Returns:
- the neitherpredicate
- Throws:
- NullPointerException- if either predicate is null
- See Also:
 
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nonePredicateCreate a new Predicate that returns true if none of the specified predicates are true. The predicates are checked in iterator order. If the collection of predicates is empty, then this predicate returns true.- Type Parameters:
- T- the type that the predicate queries
- Parameters:
- predicates- a collection of predicates to check, may not be null
- Returns:
- the nonepredicate
- Throws:
- NullPointerException- if the predicates collection is null
- NullPointerException- if any predicate in the collection is null
- See Also:
 
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nonePredicateCreate a new Predicate that returns true if none of the specified predicates are true. If the array of predicates is empty, then this predicate returns true.- Type Parameters:
- T- the type that the predicate queries
- Parameters:
- predicates- an array of predicates to check, may not be null
- Returns:
- the nonepredicate
- Throws:
- NullPointerException- if the predicates array is null
- NullPointerException- if any predicate in the array is null
- See Also:
 
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notNullPredicateGets a Predicate that checks if the input object passed in is not null.- Type Parameters:
- T- the type that the predicate queries
- Returns:
- the predicate
- See Also:
 
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notPredicateCreate a new Predicate that returns true if the specified predicate returns false and vice versa.- Type Parameters:
- T- the type that the predicate queries
- Parameters:
- predicate- the predicate to not
- Returns:
- the notpredicate
- Throws:
- NullPointerException- if the predicate is null
- See Also:
 
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nullIsExceptionPredicateGets a Predicate that throws an exception if the input object is null, otherwise it calls the specified Predicate. This allows null handling behavior to be added to Predicates that don't support nulls.- Type Parameters:
- T- the type that the predicate queries
- Parameters:
- predicate- the predicate to wrap, may not be null
- Returns:
- the predicate
- Throws:
- NullPointerException- if the predicate is null.
- See Also:
 
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nullIsFalsePredicateGets a Predicate that returns false if the input object is null, otherwise it calls the specified Predicate. This allows null handling behavior to be added to Predicates that don't support nulls.- Type Parameters:
- T- the type that the predicate queries
- Parameters:
- predicate- the predicate to wrap, may not be null
- Returns:
- the predicate
- Throws:
- NullPointerException- if the predicate is null.
- See Also:
 
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nullIsTruePredicateGets a Predicate that returns true if the input object is null, otherwise it calls the specified Predicate. This allows null handling behavior to be added to Predicates that don't support nulls.- Type Parameters:
- T- the type that the predicate queries
- Parameters:
- predicate- the predicate to wrap, may not be null
- Returns:
- the predicate
- Throws:
- NullPointerException- if the predicate is null.
- See Also:
 
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nullPredicateGets a Predicate that checks if the input object passed in is null.- Type Parameters:
- T- the type that the predicate queries
- Returns:
- the predicate
- See Also:
 
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onePredicateCreate a new Predicate that returns true if only one of the specified predicates are true. The predicates are checked in iterator order. If the collection of predicates is empty, then this predicate returns false.- Type Parameters:
- T- the type that the predicate queries
- Parameters:
- predicates- a collection of predicates to check, may not be null
- Returns:
- the onepredicate
- Throws:
- NullPointerException- if the predicates collection is null
- NullPointerException- if any predicate in the collection is null
- See Also:
 
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onePredicateCreate a new Predicate that returns true if only one of the specified predicates are true. If the array of predicates is empty, then this predicate returns false.- Type Parameters:
- T- the type that the predicate queries
- Parameters:
- predicates- an array of predicates to check, may not be null
- Returns:
- the onepredicate
- Throws:
- NullPointerException- if the predicates array is null
- NullPointerException- if any predicate in the array is null
- See Also:
 
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orPredicatepublic static <T> Predicate<T> orPredicate(Predicate<? super T> predicate1, Predicate<? super T> predicate2) Create a new Predicate that returns true if either of the specified predicates are true.- Type Parameters:
- T- the type that the predicate queries
- Parameters:
- predicate1- the first predicate, may not be null
- predicate2- the second predicate, may not be null
- Returns:
- the orpredicate
- Throws:
- NullPointerException- if either predicate is null
- See Also:
 
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transformedPredicatepublic static <T> Predicate<T> transformedPredicate(Transformer<? super T, ? extends T> transformer, Predicate<? super T> predicate) Creates a predicate that transforms the input object before passing it to the predicate.- Type Parameters:
- T- the type that the predicate queries
- Parameters:
- transformer- the transformer to call first
- predicate- the predicate to call with the result of the transform
- Returns:
- the predicate
- Throws:
- NullPointerException- if the transformer or the predicate is null
- Since:
- 3.1
- See Also:
 
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truePredicateGets a Predicate that always returns true.- Type Parameters:
- T- the type that the predicate queries
- Returns:
- the predicate
- See Also:
 
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uniquePredicateCreates a Predicate that returns true the first time an object is encountered, and false if the same object is received again. The comparison is by equals(). Anullinput object is accepted and will return true the first time, and false subsequently as well.- Type Parameters:
- T- the type that the predicate queries
- Returns:
- the predicate
- See Also:
 
 
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