com.google.common.base.Predicate Maven / Gradle / Ivy
/*
* Copyright (C) 2007 The Guava Authors
*
* Licensed 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 com.google.common.base;
import com.google.common.annotations.GwtCompatible;
import com.google.errorprone.annotations.CanIgnoreReturnValue;
import javax.annotation.Nullable;
/**
* Legacy version of {@link java.util.function.Predicate}. Determines a true or false value for a
* given input.
*
* As this interface extends {@code java.util.function.Predicate}, an instance of this type may
* be used as a {@code Predicate} directly. To use a {@code java.util.function.Predicate} where a
* {@code com.google.common.base.Predicate} is expected, use the method reference {@code
* predicate::test}.
*
*
This interface is now a legacy type. Use {@code java.util.function.Predicate} (or the
* appropriate primitive specialization such as {@code IntPredicate}) instead whenever possible.
* Otherwise, at least reduce explicit dependencies on this type by using lambda expressions
* or method references instead of classes, leaving your code easier to migrate in the future.
*
*
The {@link Predicates} class provides common predicates and related utilities.
*
*
See the Guava User Guide article on
* the use of {@code
* Predicate}.
*
* @author Kevin Bourrillion
* @since 2.0
*/
@FunctionalInterface
@GwtCompatible
public interface Predicate extends java.util.function.Predicate {
/**
* Returns the result of applying this predicate to {@code input} (Java 8 users, see notes in the
* class documentation above). This method is generally expected, but not absolutely
* required, to have the following properties:
*
*
* - Its execution does not cause any observable side effects.
*
- The computation is consistent with equals; that is, {@link Objects#equal
* Objects.equal}{@code (a, b)} implies that {@code predicate.apply(a) ==
* predicate.apply(b))}.
*
*
* @throws NullPointerException if {@code input} is null and this predicate does not accept null
* arguments
*/
@CanIgnoreReturnValue
boolean apply(@Nullable T input);
/**
* Indicates whether another object is equal to this predicate.
*
* Most implementations will have no reason to override the behavior of {@link Object#equals}.
* However, an implementation may also choose to return {@code true} whenever {@code object} is a
* {@link Predicate} that it considers interchangeable with this one. "Interchangeable"
* typically means that {@code this.apply(t) == that.apply(t)} for all {@code t} of type
* {@code T}). Note that a {@code false} result from this method does not imply that the
* predicates are known not to be interchangeable.
*/
@Override
boolean equals(@Nullable Object object);
@Override
default boolean test(@Nullable T input) {
return apply(input);
}
}