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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) 2014-2024 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 java.util.function.Function;
import java.util.function.Predicate;

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

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

/**
 * Extends {@link IHasChildren} by indicating that the child items are sorted!
 *
 * @author Philip Helger
 * @param 
 *        The type of the children.
 */
public interface IHasChildrenSorted  extends IHasChildren 
{
  /**
   * @return A ordered list of child elements. May be null if no
   *         children are present.
   */
  @Nullable
  ICommonsList  getAllChildren ();

  /**
   * Get the child node at the specified index
   *
   * @param nIndex
   *        The index to be queried. May not be < 0 or ≥ the number of
   *        children
   * @return The child at the specified index or null if the index
   *         is invalid.
   * @throws IndexOutOfBoundsException
   *         in case the index is invalid
   */
  @Nullable
  CHILDTYPE getChildAtIndex (@Nonnegative int nIndex);

  /**
   * Get the first child node or null if no child is present
   *
   * @return The first child or null.
   */
  @Nullable
  default CHILDTYPE getFirstChild ()
  {
    return getChildAtIndex (0);
  }

  /**
   * Find the first direct child that matches the passed predicate.
   *
   * @param aFilter
   *        The filter that is applied on each direct child node. May not be
   *        null.
   * @return null if no direct child matches the passed filter or
   *         if no child is present at all.
   */
  @Nullable
  default CHILDTYPE findFirstChild (@Nonnull final Predicate  aFilter)
  {
    if (hasNoChildren ())
      return null;
    return getChildren ().findFirst (aFilter);
  }

  /**
   * Find the first direct child that matches the passed predicate.
   *
   * @param aFilter
   *        The filter that is applied on each direct child node. May not be
   *        null.
   * @param aMapper
   *        The mapping function from micro node to the target type. May not be
   *        null.
   * @return null if no direct child matches the passed filter or
   *         if no child is present at all.
   * @param 
   *        The destination type to be mapped to
   */
  @Nullable
  default  DSTTYPE findFirstChildMapped (@Nonnull final Predicate  aFilter,
                                                  @Nonnull final Function  aMapper)
  {
    if (hasNoChildren ())
      return null;
    return getChildren ().findFirstMapped (aFilter, aMapper);
  }

  /**
   * Get the last child node or null if no child is present
   *
   * @return The last child or null.
   */
  @Nullable
  default CHILDTYPE getLastChild ()
  {
    return getChildAtIndex (getChildCount () - 1);
  }
}