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The OpenTripPlanner multimodal journey planning system
There is a newer version: 2.5.0
package org.opentripplanner.util;

import gnu.trove.map.TLongObjectMap;

import java.util.ArrayList;
import java.util.Collection;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.function.Function;
import java.util.stream.Collectors;

public class MapUtils {

    public static final  void addToMapSet(TLongObjectMap> mapSet, long key, U value) {
        Set set = mapSet.get(key);
        if (set == null) {
            set = new HashSet();
            mapSet.put(key, set);
        }
        set.add(value);
    }

    public static final  void addToMapList(Map> mapList, T key, U value) {
        List list = mapList.get(key);
        if (list == null) {
            list = new ArrayList();
            mapList.put(key, list);
        }
        list.add(value);
    }

    public static final  boolean addToMaxMap(Map map, T key, double value) {
        Double oldValue = map.get(key);
        if (oldValue == null || value > oldValue) {
            map.put(key, value);
            return true;
        }
        return false;
    }

    public static  void addToMapListUnique(Map> mapList,
            T key, List values) {
        List list = mapList.get(key);
        if (list == null) {
            list = new ArrayList(values.size());
            mapList.put(key, list);
        }
        for (U value : values) {
            if (!list.contains(value)) {
                list.add(value);
            }
        }
    }

    public static > void mergeInUnique(Map mapList,
            Map from) {
        for (Map.Entry entry : from.entrySet()) {
            T key = entry.getKey();
            V value = entry.getValue();
            V originalValue = mapList.get(key);
            if (originalValue != null) {
                HashSet originalSet = new HashSet(originalValue);
                for (U item : value) {
                    if (!originalSet.contains(item))
                        originalValue.add(item);
                }
            } else {
                mapList.put(key, value);
            }
        }
    }

    /**
     * Map a collection of objects of type S to a list of type T using the
     * provided mapping function.
     * 
     * Nullsafe: if entities is null, then null is returned.
     */
    public static  List mapToList(Collection entities, Function mapper) {
        return entities == null ? null : entities.stream().map(mapper).collect(Collectors.toList());
    }
}