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"Library to load OSM data into an Atlas format"

There is a newer version: 7.0.8

package org.openstreetmap.atlas.utilities.collections;

import java.util.HashMap;
import java.util.Map;

import org.openstreetmap.atlas.exception.CoreException;

/**
 * @author matthieun
 */
public final class Maps
{
    /**
     * Return a {@link HashMap} from a even number of keys and values of the same type
     *
     * @param items
     *            a even number of keys and values of the same type
     * @param 
     *            The type for the map
     * @return A {@link HashMap} translated from the keys and values in items
     */
    @SafeVarargs
    public static  Map hashMap(final T... items)
    {
        if (items.length % 2 != 0)
        {
            throw new CoreException("Needs to have an even number of arguments");
        }
        final Map result = new HashMap<>();
        for (int i = 0; i < items.length; i += 2)
        {
            result.put(items[i], items[i + 1]);
        }
        return result;
    }

    public static Map stringMap(final String... items)
    {
        return hashMap(items);
    }

    @SafeVarargs
    public static  Map withMaps(final boolean rejectCollisions,
            final Map... items)
    {
        if (items.length == 0)
        {
            return new HashMap<>();
        }
        if (items.length == 1)
        {
            return items[0];
        }
        final Map result = new HashMap<>();
        for (final Map item : items)
        {
            for (final Map.Entry entry : item.entrySet())
            {
                if (rejectCollisions && result.containsKey(entry.getKey()))
                {
                    throw new CoreException("Cannot merge maps! Collision on key.");
                }
                result.put(entry.getKey(), entry.getValue());
            }
        }
        return result;
    }

    @SafeVarargs
    public static  Map withMaps(final Map... items)
    {
        return withMaps(true, items);
    }

    private Maps()
    {
    }
}