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package org.apache.commons.collections4;
Defines a functor interface implemented by classes that perform a predicate
test on an object.
A Predicate
is the object equivalent of an if
statement.
It uses the input object to return a true or false value, and is often used in
validation or filtering.
Standard implementations of common predicates are provided by PredicateUtils
. These include true, false, instanceof, equals, and, or, not, method invokation and null testing.
Type parameters: - <T> – the type that the predicate queries
Since: 1.0
/**
* Defines a functor interface implemented by classes that perform a predicate
* test on an object.
* <p>
* A <code>Predicate</code> is the object equivalent of an <code>if</code> statement.
* It uses the input object to return a true or false value, and is often used in
* validation or filtering.
* <p>
* Standard implementations of common predicates are provided by
* {@link PredicateUtils}. These include true, false, instanceof, equals, and,
* or, not, method invokation and null testing.
*
* @param <T> the type that the predicate queries
*
* @since 1.0
*/
public interface Predicate<T> {
Use the specified parameter to perform a test that returns true or false.
Params: - object – the object to evaluate, should not be changed
Throws: - ClassCastException – (runtime) if the input is the wrong class
- IllegalArgumentException – (runtime) if the input is invalid
- FunctorException – (runtime) if the predicate encounters a problem
Returns: true or false
/**
* Use the specified parameter to perform a test that returns true or false.
*
* @param object the object to evaluate, should not be changed
* @return true or false
* @throws ClassCastException (runtime) if the input is the wrong class
* @throws IllegalArgumentException (runtime) if the input is invalid
* @throws FunctorException (runtime) if the predicate encounters a problem
*/
boolean evaluate(T object);
}