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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 java.util.function.Supplier;

import javax.annotation.Nullable;

/**
 * Base interface for wrapping an object within another object.
 *
 * @author Philip Helger
 * @param 
 *        The type of the wrapped object.
 */
@FunctionalInterface
public interface IWrapper  extends Supplier 
{
  /**
   * @return The currently wrapped object. May be null.
   */
  @Nullable
  DATATYPE get ();

  /**
   * @return true if the contained value is not null,
   *         false if it is null.
   */
  default boolean isSet ()
  {
    return get () != null;
  }

  /**
   * @return true if the contained value is null,
   *         false if it is not null.
   */
  default boolean isNotSet ()
  {
    return get () == null;
  }
}