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/*
 * Copyright (C) 2010 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 shaded.shaded.com.google.common.base;

import shaded.shaded.com.google.common.annotations.Beta;
import shaded.shaded.com.google.common.annotations.GwtCompatible;

import java.io.Serializable;

/**
 * Contains static factory methods for creating {@code Equivalence} instances.
 *
 * 

All methods return serializable instances. * * @author Bob Lee * @author Kurt Alfred Kluever * @author Gregory Kick * @since 4.0 */ @Beta @GwtCompatible public final class Equivalences { private Equivalences() {} /** * Returns an equivalence that delegates to {@link Object#equals} and {@link Object#hashCode}. * {@link Equivalence#equivalent} returns {@code true} if both values are null, or if neither * value is null and {@link Object#equals} returns {@code true}. {@link Equivalence#hash} returns * {@code 0} if passed a null value. * * @since 8.0 (present null-friendly behavior) * @since 4.0 (otherwise) */ public static Equivalence equals() { return Equals.INSTANCE; } /** * Returns an equivalence that uses {@code ==} to compare values and {@link * System#identityHashCode(Object)} to compute the hash code. {@link Equivalence#equivalent} * returns {@code true} if {@code a == b}, including in the case that a and b are both null. */ public static Equivalence identity() { return Identity.INSTANCE; } private static final class Equals extends Equivalence implements Serializable { static final Equals INSTANCE = new Equals(); @Override protected boolean doEquivalent(Object a, Object b) { return a.equals(b); } @Override public int doHash(Object o) { return o.hashCode(); } private Object readResolve() { return INSTANCE; } private static final long serialVersionUID = 1; } private static final class Identity extends Equivalence implements Serializable { static final Identity INSTANCE = new Identity(); @Override protected boolean doEquivalent(Object a, Object b) { return false; } @Override protected int doHash(Object o) { return System.identityHashCode(o); } private Object readResolve() { return INSTANCE; } private static final long serialVersionUID = 1; } }