74 lines
2.5 KiB
Java
74 lines
2.5 KiB
Java
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/*
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* Copyright (C) 2007 The Guava Authors
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.google.common.base;
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import javax.annotation.Nullable;
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import com.google.common.annotations.GwtCompatible;
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/**
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* Determines a true or false value for a given input.
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*
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* <p>
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* The {@link Predicates} class provides common predicates and related
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* utilities.
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*
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* <p>
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* See the Guava User Guide article on <a href=
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* "http://code.google.com/p/guava-libraries/wiki/FunctionalExplained">the use
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* of {@code
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* Predicate}</a>.
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*
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* @author Kevin Bourrillion
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* @since 2.0 (imported from Google Collections Library)
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*/
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@GwtCompatible
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public interface Predicate<T> {
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/**
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* Returns the result of applying this predicate to {@code input}. This method
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* is <i>generally expected</i>, but not absolutely required, to have the
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* following properties:
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*
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* <ul>
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* <li>Its execution does not cause any observable side effects.
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* <li>The computation is <i>consistent with equals</i>; that is,
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* {@link Objects#equal Objects.equal}{@code (a, b)} implies that
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* {@code predicate.apply(a) ==
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* predicate.apply(b))}.
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* </ul>
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*
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* @throws NullPointerException if {@code input} is null and this predicate does
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* not accept null arguments
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*/
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boolean apply(@Nullable T input);
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/**
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* Indicates whether another object is equal to this predicate.
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*
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* <p>
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* Most implementations will have no reason to override the behavior of
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* {@link Object#equals}. However, an implementation may also choose to return
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* {@code true} whenever {@code object} is a {@link Predicate} that it considers
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* <i>interchangeable</i> with this one. "Interchangeable" <i>typically</i>
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* means that {@code this.apply(t) == that.apply(t)} for all {@code t} of type
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* {@code T}). Note that a {@code false} result from this method does not imply
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* that the predicates are known <i>not</i> to be interchangeable.
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*/
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@Override
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boolean equals(@Nullable Object object);
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}
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