com.twitter.heron.api.Pair Maven / Gradle / Ivy

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//  Copyright 2017 Twitter. All rights reserved.
//
//  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.twitter.heron.api;

import java.io.Serializable;

/**
 * A pair of values.
 *
 * @param  the type of the first value
 * @param  the type of the second value
 */
public final class Pair implements Serializable {

  private static final long serialVersionUID = 3926373357946515821L;
  /**
   * The first value
   */
  private final T1 first;
  /**
   * The second value
   */
  private final T2 second;

  /**
   * Constructs a new pair of values
   *
   * @param first the first value
   * @param second the second value
   */
  private Pair(T1 first, T2 second) {
    this.first = first;
    this.second = second;
  }

  /**
   * Returns the first value in a pair.
   *
   * @return the first value
   */
  public T1 getFirst() {
    return first;
  }

  /**
   * Returns the second value in a pair.
   *
   * @return the second value
   */
  public T2 getSecond() {
    return second;
  }

  /**
   * Constructs a new pair of values.
   *
   * @param first the first value
   * @param second the second value
   * @param  the type of the first value
   * @param  the type of the second value
   * @return a new pair of values
   */
  public static  Pair of(T1 first, T2 second) {
    return new Pair<>(first, second);
  }

  @Override
  public boolean equals(Object o) {
    if (this == o) {
      return true;
    }
    if (o == null || getClass() != o.getClass()) {
      return false;
    }

    Pair pair = (Pair) o;

    if (first != null ? !first.equals(pair.first) : pair.first != null) {
      return false;
    }
    return second != null ? second.equals(pair.second) : pair.second == null;

  }

  @Override
  public int hashCode() {
    int result = first != null ? first.hashCode() : 0;
    result = 31 * result + (second != null ? second.hashCode() : 0);
    return result;
  }

  @Override
  public String toString() {
    return "(" + first + ", " + second + ')';
  }
}