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Special Java 1.8+ Library with extended collection related functionality
There is a newer version: 9.5.5
/**
 * Copyright (C) 2014-2020 Philip Helger (www.helger.com)
 * philip[at]helger[dot]com
 *
 * 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.helger.collection.pair;

import javax.annotation.Nonnull;
import javax.annotation.Nullable;
import javax.annotation.concurrent.NotThreadSafe;

import com.helger.commons.ValueEnforcer;
import com.helger.commons.equals.EqualsHelper;
import com.helger.commons.hashcode.HashCodeGenerator;
import com.helger.commons.lang.ICloneable;
import com.helger.commons.state.EChange;
import com.helger.commons.string.ToStringGenerator;

/**
 * A generic pair class. It wraps two objects of arbitrary type. If you just
 * want to wrap a single object, look at class
 * {@link com.helger.commons.wrapper.Wrapper}.
 *
 * @author Philip Helger
 * @param 
 *        First type.
 * @param 
 *        Second type.
 */
@NotThreadSafe
public final class Pair  implements
                        IMutablePair ,
                        ICloneable >
{
  private DATA1TYPE m_aFirst;
  private DATA2TYPE m_aSecond;

  public Pair ()
  {
    this (null, null);
  }

  public  Pair (@Nullable final T2 aFirst, @Nullable final U2 aSecond)
  {
    m_aFirst = aFirst;
    m_aSecond = aSecond;
  }

  public Pair (@Nonnull final IPair  rhs)
  {
    ValueEnforcer.notNull (rhs, "Pair");
    m_aFirst = rhs.getFirst ();
    m_aSecond = rhs.getSecond ();
  }

  @Nullable
  public DATA1TYPE getFirst ()
  {
    return m_aFirst;
  }

  @Nonnull
  public EChange setFirst (@Nullable final DATA1TYPE aFirst)
  {
    if (EqualsHelper.equals (aFirst, m_aFirst))
      return EChange.UNCHANGED;
    m_aFirst = aFirst;
    return EChange.CHANGED;
  }

  @Nullable
  public DATA2TYPE getSecond ()
  {
    return m_aSecond;
  }

  @Nonnull
  public EChange setSecond (@Nullable final DATA2TYPE aSecond)
  {
    if (EqualsHelper.equals (aSecond, m_aSecond))
      return EChange.UNCHANGED;
    m_aSecond = aSecond;
    return EChange.CHANGED;
  }

  @Nonnull
  public Pair  getClone ()
  {
    return new Pair <> (this);
  }

  @Override
  public boolean equals (final Object o)
  {
    if (o == this)
      return true;
    if (o == null || !getClass ().equals (o.getClass ()))
      return false;
    final Pair  rhs = (Pair ) o;
    return EqualsHelper.equals (m_aFirst, rhs.m_aFirst) && EqualsHelper.equals (m_aSecond, rhs.m_aSecond);
  }

  @Override
  public int hashCode ()
  {
    return new HashCodeGenerator (this).append (m_aFirst).append (m_aSecond).getHashCode ();
  }

  @Override
  public String toString ()
  {
    return new ToStringGenerator (null).append ("first", m_aFirst).append ("second", m_aSecond).getToString ();
  }

  @Nonnull
  public static  Pair  create (@Nullable final T aFirst, @Nullable final U aSecond)
  {
    return new Pair <> (aFirst, aSecond);
  }
}