org.apache.commons.collections4.Predicate Maven / Gradle / Ivy
Show all versions of commons-collections4 Show documentation
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
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
* {@link PredicateUtils}. These include true, false, instanceof, equals, and,
* or, not, method invokation and null testing.
*
* @param the type that the predicate queries
*
* @since 1.0
*/
public interface Predicate {
/**
* 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);
}