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/*
* Copyright 2015-2024 the original author or 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
*
* https://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.springframework.data.util;
import java.util.Map;
import java.util.stream.Collector;
import java.util.stream.Collectors;
import java.util.stream.Stream;
import org.springframework.lang.Nullable;
import org.springframework.util.Assert;
import org.springframework.util.ObjectUtils;
/**
* A tuple of things.
*
* @author Tobias Trelle
* @author Oliver Gierke
* @author Christoph Strobl
* @param Type of the first thing.
* @param Type of the second thing.
* @since 1.12
*/
public final class Pair {
private final S first;
private final T second;
private Pair(S first, T second) {
Assert.notNull(first, "First must not be null");
Assert.notNull(second, "Second must not be null");
this.first = first;
this.second = second;
}
/**
* Creates a new {@link Pair} for the given elements.
*
* @param first must not be {@literal null}.
* @param second must not be {@literal null}.
* @return
*/
public static Pair of(S first, T second) {
return new Pair<>(first, second);
}
/**
* Returns the first element of the {@link Pair}.
*
* @return
*/
public S getFirst() {
return first;
}
/**
* Returns the second element of the {@link Pair}.
*
* @return
*/
public T getSecond() {
return second;
}
/**
* A collector to create a {@link Map} from a {@link Stream} of {@link Pair}s.
*
* @return
*/
public static Collector, ?, Map> toMap() {
return Collectors.toMap(Pair::getFirst, Pair::getSecond);
}
@Override
public boolean equals(@Nullable Object o) {
if (this == o) {
return true;
}
if (!(o instanceof Pair pair)) {
return false;
}
if (!ObjectUtils.nullSafeEquals(first, pair.first)) {
return false;
}
return ObjectUtils.nullSafeEquals(second, pair.second);
}
@Override
public int hashCode() {
int result = ObjectUtils.nullSafeHashCode(first);
result = 31 * result + ObjectUtils.nullSafeHashCode(second);
return result;
}
@Override
public String toString() {
return String.format("%s->%s", this.first, this.second);
}
}