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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.compare;

import java.io.Serializable;
import java.text.Collator;
import java.util.Comparator;
import java.util.Locale;
import java.util.function.Function;

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

import com.helger.commons.ValueEnforcer;

/**
 * A special interface that combines {@link Comparator} and {@link Serializable}
 * for easier reuse since {@link Comparator}s should be Serializable.
 *
 * @author Philip Helger
 * @param 
 *        The data type to be compared
 */
@NotThreadSafe
@FunctionalInterface
public interface IComparator  extends Comparator , Serializable
{
  @Nonnull
  static Comparator  getComparatorCollating (@Nullable final Locale aSortLocale)
  {
    return getComparatorCollating (CollatorHelper.getCollatorSpaceBeforeDot (aSortLocale));
  }

  @Nonnull
  static Comparator  getComparatorCollating (@Nonnull final Collator aCollator)
  {
    ValueEnforcer.notNull (aCollator, "Collator");
    return Comparator.nullsFirst (aCollator::compare);
  }

  @Nonnull
  static  Comparator  getComparatorCollating (@Nonnull final Function  aMapper, @Nullable final Locale aSortLocale)
  {
    return Comparator. comparing (aMapper, getComparatorCollating (aSortLocale));
  }

  @Nonnull
  static  Comparator  getComparatorCollating (@Nonnull final Function  aMapper, @Nonnull final Collator aCollator)
  {
    return Comparator. comparing (aMapper, getComparatorCollating (aCollator));
  }

  @Nonnull
  static IComparator  getComparatorStringLongestFirst ()
  {
    return getComparatorStringLongestFirst (CompareHelper.DEFAULT_NULL_VALUES_COME_FIRST);
  }

  @Nonnull
  static IComparator  getComparatorStringLongestFirst (final boolean bNullValuesComeFirst)
  {
    return (c1, c2) -> CompareHelper.compare (c1, c2, (o1, o2) -> {
      final int ret = o2.length () - o1.length ();
      return ret != 0 ? ret : o1.compareTo (o2);
    }, bNullValuesComeFirst);
  }

  @Nonnull
  static IComparator  getComparatorStringShortestFirst ()
  {
    return getComparatorStringShortestFirst (CompareHelper.DEFAULT_NULL_VALUES_COME_FIRST);
  }

  @Nonnull
  static IComparator  getComparatorStringShortestFirst (final boolean bNullValuesComeFirst)
  {
    return (c1, c2) -> CompareHelper.compare (c1, c2, (o1, o2) -> {
      final int ret = o1.length () - o2.length ();
      return ret != 0 ? ret : o1.compareTo (o2);
    }, bNullValuesComeFirst);
  }

  @Nonnull
  static IComparator  getComparatorStringIgnoreCase ()
  {
    return getComparatorStringIgnoreCase (CompareHelper.DEFAULT_NULL_VALUES_COME_FIRST);
  }

  @Nonnull
  static IComparator  getComparatorStringIgnoreCase (final boolean bNullValuesComeFirst)
  {
    return (c1, c2) -> CompareHelper.compareIgnoreCase (c1, c2, bNullValuesComeFirst);
  }
}