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Java 1.8+ Library with tons of utility classes required in all projects

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/*
 * Copyright (C) 2014-2024 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.hierarchy;

import javax.annotation.Nonnegative;
import javax.annotation.Nullable;

import com.helger.commons.collection.impl.ICommonsList;

/**
 * This interface can be used to generically resolved children of a certain
 * object in a sorted way.
 *
 * @author Philip Helger
 * @param 
 *        The type of the children to retrieve.
 */
public interface IChildrenProviderSorted  extends IChildrenProvider 
{
  /**
   * Get the children of the passed object.
   *
   * @param aCurrent
   *        The object to determine the children of. May be null
   *        depending on the concrete implementation.
   * @return The child objects, or null if there are no children.
   *         If null is passed, the resolver is expected to return
   *         any possible top level (root) elements. This method may NOT return
   *         null if the call to {@link #hasChildren(Object)} with
   *         the same object returned true.
   */
  @Nullable
  ICommonsList  getAllChildren (@Nullable CHILDTYPE aCurrent);

  /**
   * Get the child of the passed object at the given index. It is assumed that
   * objects are accessed in exactly the same order as they are delivered by
   * {@link #getAllChildren(Object)}.
   *
   * @param aCurrent
   *        The object to get the child of. May be null depending
   *        on the concrete implementation.
   * @param nIndex
   *        The index to retrieve the child at.
   * @return The child at the specified index. May not be < 0.
   * @throws IndexOutOfBoundsException
   *         in case the specified index is invalid.
   */
  @Nullable
  CHILDTYPE getChildAtIndex (@Nullable CHILDTYPE aCurrent, @Nonnegative int nIndex);
}