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Java 1.8+ Library with tons of utility classes required in all projects
There is a newer version: 11.1.10
/*
 * Copyright (C) 2014-2022 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.commons.wrapper;

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

import com.helger.commons.ValueEnforcer;
import com.helger.commons.annotation.ReturnsMutableCopy;
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;

/**
 * This is a stupid wrapper around any object. Its original purpose was the
 * encapsulation of return values from within an anonymous class.
 *
 * @author Philip Helger
 * @param 
 *        The type of object to be wrapped.
 */
@NotThreadSafe
public class Wrapper  implements IMutableWrapper , ICloneable >
{
  private DATATYPE m_aObj;

  /**
   * Default constructor. Wraps a null values.
   */
  public Wrapper ()
  {}

  /**
   * Constructor with an existing object.
   *
   * @param aObj
   *        The existing object. May be null.
   */
  public Wrapper (@Nullable final DATATYPE aObj)
  {
    m_aObj = aObj;
  }

  /**
   * Copy constructor. Only takes wrappers of the same type.
   *
   * @param aRhs
   *        The other wrapper to use. May not be null.
   */
  public Wrapper (@Nonnull final IWrapper  aRhs)
  {
    m_aObj = ValueEnforcer.notNull (aRhs, "Wrapper").get ();
  }

  @Nullable
  public DATATYPE get ()
  {
    return m_aObj;
  }

  @Nonnull
  public EChange set (@Nullable final DATATYPE aObj)
  {
    if (EqualsHelper.equals (m_aObj, aObj))
      return EChange.UNCHANGED;
    m_aObj = aObj;
    return EChange.CHANGED;
  }

  @Nonnull
  @ReturnsMutableCopy
  public Wrapper  getClone ()
  {
    return new Wrapper <> (m_aObj);
  }

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

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

  @Override
  public String toString ()
  {
    return new ToStringGenerator (this).append ("obj", m_aObj).getToString ();
  }
}