Class ComparatorPredicate<T>
- Type Parameters:
T- the type of the input to the predicate.
- All Implemented Interfaces:
Serializable,Predicate<T>,Predicate<T>
In order to demonstrate the use of the predicate, the following variables are declared:
Integer ONE = Integer.valueOf(1);
Integer TWO = Integer.valueOf(2);
Comparator comparator = new Comparator() {
public int compare(Object first, Object second) {
return ((Integer) second) - ((Integer) first);
}
};
Using the declared variables, the ComparatorPredicate can be used in the
following way:
ComparatorPredicate.comparatorPredicate(ONE, comparator).test(TWO);
The input variable TWO in compared to the stored variable ONE using
the supplied comparator. This is the default usage of the predicate and will return
true if the underlying comparator returns 0. In addition to the default
usage of the predicate, it is possible to evaluate the comparator's result in several ways. The
following ComparatorPredicate.Criterion enumeration values are provided by the predicate:
- EQUAL
- GREATER
- GREATER_OR_EQUAL
- LESS
- LESS_OR_EQUAL
The following examples demonstrates how these constants can be used in order to manipulate the evaluation of a comparator result.
ComparatorPredicate.comparatorPredicate(ONE, comparator,ComparatorPredicate.Criterion.GREATER).test(TWO);
The input variable TWO is compared to the stored variable ONE using the supplied comparator
using the GREATER evaluation criterion constant. This instructs the predicate to
return true if the comparator returns a value greater than 0.
- Since:
- 4.0
- See Also:
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Nested Class Summary
Nested ClassesModifier and TypeClassDescriptionstatic enumEnumerates the comparator criteria. -
Constructor Summary
ConstructorsConstructorDescriptionComparatorPredicate(T object, Comparator<T> comparator, ComparatorPredicate.Criterion criterion) Constructor that performs no validation. -
Method Summary
Modifier and TypeMethodDescriptionstatic <T> Predicate<T> comparatorPredicate(T object, Comparator<T> comparator) Creates the comparator predicatestatic <T> Predicate<T> comparatorPredicate(T object, Comparator<T> comparator, ComparatorPredicate.Criterion criterion) Creates the comparator predicatebooleanEvaluates the predicate.Methods inherited from class org.apache.commons.collections4.functors.AbstractPredicate
evaluate
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Constructor Details
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ComparatorPredicate
public ComparatorPredicate(T object, Comparator<T> comparator, ComparatorPredicate.Criterion criterion) Constructor that performs no validation. UsecomparatorPredicateif you want that.- Parameters:
object- the object to compare tocomparator- the comparator to use for comparisoncriterion- the criterion to use to evaluate comparison
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Method Details
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comparatorPredicate
Creates the comparator predicate- Type Parameters:
T- the type that the predicate queries- Parameters:
object- the object to compare tocomparator- the comparator to use for comparison- Returns:
- the predicate
- Throws:
NullPointerException- if comparator is null
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comparatorPredicate
public static <T> Predicate<T> comparatorPredicate(T object, Comparator<T> comparator, ComparatorPredicate.Criterion criterion) Creates the comparator predicate- Type Parameters:
T- the type that the predicate queries- Parameters:
object- the object to compare tocomparator- the comparator to use for comparisoncriterion- the criterion to use to evaluate comparison- Returns:
- the predicate
- Throws:
NullPointerException- if comparator or criterion is null
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test
Evaluates the predicate. The predicate evaluates totruein the following cases:comparator.compare(object, input) == 0 && criterion == EQUALcomparator.compare(object, input) < 0 && criterion == LESScomparator.compare(object, input) > 0 && criterion == GREATERcomparator.compare(object, input) >= 0 && criterion == GREATER_OR_EQUALcomparator.compare(object, input) <= 0 && criterion == LESS_OR_EQUAL
- Specified by:
testin interfacePredicate<T>- Specified by:
testin interfacePredicate<T>- Parameters:
target- the target object to compare to- Returns:
trueif the comparison succeeds according to the selected criterion- Throws:
IllegalStateException- if the criterion is invalid (really not possible)- See Also:
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