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java.lang.Object
org.apache.commons.collections.PredicateUtils
public class PredicateUtils
extends java.lang.Object
PredicateUtils
provides reference implementations and utilities
for the Predicate functor interface. The supplied predicates are:
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public static Predicate allPredicate(Collection predicates)
Create a new Predicate that returns true only if all of the specified predicates are true. The predicates are checked in iterator order.
- Parameters:
predicates
- a collection of predicates to check, may not be null
- Returns:
- the
all
predicate
- See Also:
AllPredicate
public static Predicate allPredicate(Predicate[] predicates)
Create a new Predicate that returns true only if all of the specified predicates are true.
- Parameters:
predicates
- an array of predicates to check, may not be null
- Returns:
- the
all
predicate
- See Also:
AllPredicate
public static Predicate andPredicate(Predicate predicate1, Predicate predicate2)
Create a new Predicate that returns true only if both of the specified predicates are true.
- Parameters:
predicate1
- the first predicate, may not be nullpredicate2
- the second predicate, may not be null
- Returns:
- the
and
predicate
- See Also:
AndPredicate
public static Predicate anyPredicate(Collection predicates)
Create a new Predicate that returns true if any of the specified predicates are true. The predicates are checked in iterator order.
- Parameters:
predicates
- a collection of predicates to check, may not be null
- Returns:
- the
any
predicate
- See Also:
AnyPredicate
public static Predicate anyPredicate(Predicate[] predicates)
Create a new Predicate that returns true if any of the specified predicates are true.
- Parameters:
predicates
- an array of predicates to check, may not be null
- Returns:
- the
any
predicate
- See Also:
AnyPredicate
public static Predicate asPredicate(Transformer transformer)
Create a new Predicate that wraps a Transformer. The Transformer must return either Boolean.TRUE or Boolean.FALSE otherwise a PredicateException will be thrown.
- Parameters:
transformer
- the transformer to wrap, may not be null
- Returns:
- the transformer wrapping predicate
- See Also:
TransformerPredicate
public static Predicate eitherPredicate(Predicate predicate1, Predicate predicate2)
Create a new Predicate that returns true if one, but not both, of the specified predicates are true.
- Parameters:
predicate1
- the first predicate, may not be nullpredicate2
- the second predicate, may not be null
- Returns:
- the
either
predicate
- See Also:
OnePredicate
public static Predicate equalPredicate(Object value)
Creates a Predicate that checks if the input object is equal to the specified object using equals().
- Parameters:
value
- the value to compare against
- Returns:
- the predicate
- See Also:
EqualPredicate
public static Predicate exceptionPredicate()
Gets a Predicate that always throws an exception. This could be useful during testing as a placeholder.
- Returns:
- the predicate
- See Also:
ExceptionPredicate
public static Predicate falsePredicate()
Gets a Predicate that always returns false.
- Returns:
- the predicate
- See Also:
FalsePredicate
public static Predicate identityPredicate(Object value)
Creates a Predicate that checks if the input object is equal to the specified object by identity.
- Parameters:
value
- the value to compare against
- Returns:
- the predicate
- See Also:
IdentityPredicate
public static Predicate instanceofPredicate(Class type)
Creates a Predicate that checks if the object passed in is of a particular type, using instanceof. Anull
input object will returnfalse
.
- Parameters:
type
- the type to check for, may not be null
- Returns:
- the predicate
- See Also:
InstanceofPredicate
public static Predicate invokerPredicate(String methodName)
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 theisEmpty
method on the input object to determine the predicate result.
- Parameters:
methodName
- the method name to call on the input object, may not be null
- Returns:
- the predicate
- See Also:
InvokerTransformer
,TransformerPredicate
public static Predicate 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 theisEmpty
method on the input object to determine the predicate result.
- Parameters:
methodName
- the method name to call on the input object, may not be nullparamTypes
- the parameter typesargs
- the arguments
- Returns:
- the predicate
- See Also:
InvokerTransformer
,TransformerPredicate
public static Predicate neitherPredicate(Predicate predicate1, Predicate predicate2)
Create a new Predicate that returns true if neither of the specified predicates are true.
- Parameters:
predicate1
- the first predicate, may not be nullpredicate2
- the second predicate, may not be null
- Returns:
- the
neither
predicate
- See Also:
NonePredicate
public static Predicate nonePredicate(Collection predicates)
Create a new Predicate that returns true if none of the specified predicates are true. The predicates are checked in iterator order.
- Parameters:
predicates
- a collection of predicates to check, may not be null
- Returns:
- the
none
predicate
- See Also:
NonePredicate
public static Predicate nonePredicate(Predicate[] predicates)
Create a new Predicate that returns true if none of the specified predicates are true.
- Parameters:
predicates
- an array of predicates to check, may not be null
- Returns:
- the
none
predicate
- See Also:
NonePredicate
public static Predicate notNullPredicate()
Gets a Predicate that checks if the input object passed in is not null.
- Returns:
- the predicate
- See Also:
NotNullPredicate
public static Predicate notPredicate(Predicate predicate)
Create a new Predicate that returns true if the specified predicate returns false and vice versa.
- Parameters:
predicate
- the predicate to not
- Returns:
- the
not
predicate
- See Also:
NotPredicate
public static Predicate nullIsExceptionPredicate(Predicate predicate)
Gets a Predicate that throws an exception if the input object is null, otherwise it calls the specified Predicate. This allows null handling behaviour to be added to Predicates that don't support nulls.
- Parameters:
predicate
- the predicate to wrap, may not be null
- Returns:
- the predicate
- See Also:
NullIsExceptionPredicate
public static Predicate nullIsFalsePredicate(Predicate predicate)
Gets a Predicate that returns false if the input object is null, otherwise it calls the specified Predicate. This allows null handling behaviour to be added to Predicates that don't support nulls.
- Parameters:
predicate
- the predicate to wrap, may not be null
- Returns:
- the predicate
- See Also:
NullIsFalsePredicate
public static Predicate nullIsTruePredicate(Predicate predicate)
Gets a Predicate that returns true if the input object is null, otherwise it calls the specified Predicate. This allows null handling behaviour to be added to Predicates that don't support nulls.
- Parameters:
predicate
- the predicate to wrap, may not be null
- Returns:
- the predicate
- See Also:
NullIsTruePredicate
public static Predicate nullPredicate()
Gets a Predicate that checks if the input object passed in is null.
- Returns:
- the predicate
- See Also:
NullPredicate
public static Predicate onePredicate(Collection predicates)
Create a new Predicate that returns true if only one of the specified predicates are true. The predicates are checked in iterator order.
- Parameters:
predicates
- a collection of predicates to check, may not be null
- Returns:
- the
one
predicate
- See Also:
OnePredicate
public static Predicate onePredicate(Predicate[] predicates)
Create a new Predicate that returns true if only one of the specified predicates are true.
- Parameters:
predicates
- an array of predicates to check, may not be null
- Returns:
- the
one
predicate
- See Also:
OnePredicate
public static Predicate orPredicate(Predicate predicate1, Predicate predicate2)
Create a new Predicate that returns true if either of the specified predicates are true.
- Parameters:
predicate1
- the first predicate, may not be nullpredicate2
- the second predicate, may not be null
- Returns:
- the
or
predicate
- See Also:
OrPredicate
public static Predicate transformedPredicate(Transformer transformer, Predicate predicate)
Creates a predicate that transforms the input object before passing it to the predicate.
- Parameters:
transformer
- the transformer to call firstpredicate
- the predicate to call with the result of the transform
- Returns:
- the predicate
- Since:
- Commons Collections 3.1
- See Also:
TransformedPredicate
public static Predicate truePredicate()
Gets a Predicate that always returns true.
- Returns:
- the predicate
- See Also:
TruePredicate
public static Predicate uniquePredicate()
Creates 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(). Anull
input object is accepted and will return true the first time, and false subsequently as well.
- Returns:
- the predicate
- See Also:
UniquePredicate