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Utility library for collections, comparators and iterator classes
/**
* The MIT License
*
* Copyright (C) 2015 Asterios Raptis
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sublicense, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
* LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
* OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
* WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
package de.alpharogroup.collections.map;
import java.util.Collection;
import java.util.Comparator;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.stream.Collectors;
import de.alpharogroup.collections.list.ListFactory;
import lombok.NonNull;
import lombok.experimental.UtilityClass;
/**
* Extensions class for use with Map objects.
*
* @author Asterios Raptis
* @version 1.0
*/
@UtilityClass
public final class MapExtensions
{
/**
* Sort the given Map by its values and returns a sorted list by the values of the given Map
*
* @param
* the generic type of the key
* @param
* the generic type of the value
* @param map
* The Map to sort
* @param reversed
* the flag if the result should be in reversed order
* @return a sorted list by the values of the given Map
*/
public static > List> sortByValueAsList(
final @NonNull Map map, boolean reversed)
{
return sortByValueAsList(map,
reversed ? Comparator.reverseOrder() : Comparator.naturalOrder());
}
/**
* Sort the given Map by its values and returns a sorted list by the values of the given Map
*
* @param
* the generic type of the key
* @param
* the generic type of the value
* @param map
* The Map to sort
* @param comparator
* the comparator to sort
* @return a sorted list by the values of the given Map
*/
public static > List> sortByValueAsList(
final @NonNull Map map, final @NonNull Comparator comparator)
{
return map.entrySet().stream().sorted(Map.Entry.comparingByValue(comparator))
.collect(Collectors.toList());
}
/**
* Sort the given Map by its values and returns a sorted list by the values of the given Map
*
* @param
* the generic type of the key
* @param
* the generic type of the value
* @param map
* the Map to sort
* @param reversed
* the flag if the result should be in reversed order
* @return a sorted Map by the values of the given Map
*/
public static > Map sortByValue(
final @NonNull Map map, boolean reversed)
{
return sortByValue(map, reversed ? Comparator.reverseOrder() : Comparator.naturalOrder());
}
/**
* Sort the given Map by its values and returns a sorted list by the values of the given Map
*
* @param
* the generic type of the key
* @param
* the generic type of the value
* @param map
* the Map to sort
* @param comparator
* the comparator to sort
* @return a sorted Map by the values of the given Map
*/
public static > Map sortByValue(
final @NonNull Map map, final @NonNull Comparator comparator)
{
return map.entrySet().stream().sorted(Map.Entry.comparingByValue(comparator))
.collect(Collectors.toMap(Map.Entry::getKey, Map.Entry::getValue, (k, v) -> k,
LinkedHashMap::new));
}
/**
* Returns the first founded key from the given value or null if nothing is found.
*
* @param
* the generic type of the key
* @param
* the generic type of the value
* @param map
* The Map.
* @param value
* The value.
* @return Returns the first key from the given value or null if nothing found.
*/
public static K getKeyFromValue(final @NonNull Map map, final V value)
{
K key = null;
for (final Entry entry : map.entrySet())
{
key = entry.getKey();
if (map.get(key).equals(value))
{
break;
}
}
return key;
}
/**
* Returns a Collection from all founded keys from the given value or null if nothing found.
*
* @param
* the generic type of the key
* @param
* the generic type of the value
* @param map
* The Map.
* @param value
* The value.
* @return Returns the key from the given value or an empty Collection if nothing found.
*/
public static Collection getKeysFromValue(final @NonNull Map map, final V value)
{
final Collection keys = ListFactory.newArrayList();
for (final Entry entry : map.entrySet())
{
final V val = entry.getValue();
if (val.equals(value))
{
final K key = entry.getKey();
keys.add(key);
}
}
return keys;
}
/**
* Converts a two dimensional Array to a Map.
*
* @param
* the generic type
* @param twoDimArray
* The two dimensional Array.
* @return The map produced from the two dimensional Array.
*/
public static Map toGenericMap(final @NonNull T[][] twoDimArray)
{
final Map map = new LinkedHashMap<>();
for (final T[] element : twoDimArray)
{
final T key = element[0];
final T value = element[1];
map.put(key, value);
}
return map;
}
/**
* Converts a two dimensional String Array to a Map.
*
* @param twoDimArray
* The two dimensional String Array.
* @return The map produced from the two dimensional String Array.
*/
public static Map toMap(final String[][] twoDimArray)
{
return toGenericMap(twoDimArray);
}
}
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