CollectionUtils.java

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/* *********************************************************************** *
 * project: org.matsim.*
 *                                                                         *
 * *********************************************************************** *
 *                                                                         *
 * copyright       : (C) 2010 by the members listed in the COPYING,        *
 *                   LICENSE and WARRANTY file.                            *
 * email           : info at matsim dot org                                *
 *                                                                         *
 * *********************************************************************** *
 *                                                                         *
 *   This program is free software; you can redistribute it and/or modify  *
 *   it under the terms of the GNU General Public License as published by  *
 *   the Free Software Foundation; either version 2 of the License, or     *
 *   (at your option) any later version.                                   *
 *   See also COPYING, LICENSE and WARRANTY file                           *
 *                                                                         *
 * *********************************************************************** */

package org.matsim.core.utils.collections;

import java.util.Collection;
import java.util.Collections;
import java.util.LinkedHashSet;
import java.util.Set;

import org.matsim.api.core.v01.Id;
import org.matsim.core.utils.misc.StringUtils;

public final class CollectionUtils {
    private CollectionUtils(){} // to not intantiate

    public static <T> String idSetToString( final Set<Id<T>> values ) {
        boolean isFirst = true;
        StringBuilder str = new StringBuilder();
        for (Id<?> id : values) {
            if (!isFirst) {
                str.append(',');
            }
            str.append(id.toString());
            isFirst = false;
        }
        return str.toString();
    }

    public static String setToString( final Set<String> values ){
        return collectionToString( values );
    }
    public static String collectionToString( final Collection<String> values ) {
        boolean isFirst = true;
        StringBuilder str = new StringBuilder();
        for (String s : values) {
            if (!isFirst) {
                str.append(',');
            }
            str.append(s);
            isFirst = false;
        }
        return str.toString();
    }

    public static String [] collectionToStringArray( final Collection<String> values ) {
        return values.toArray(new String[0] );
    }

    public static String arrayToString( final String[] values ) {
        boolean isFirst = true;
        StringBuilder str = new StringBuilder();
        for (String mode : values) {
            if (!isFirst) {
                str.append(',');
            }
            str.append(mode);
            isFirst = false;
        }
        return str.toString();
    }

    public static String[] stringToArray( final String values ) {
        Set<String> tmp = stringToSet(values);
        return tmp.toArray( new String[0] );
    }

    public static Set<String> stringToSet( final String values ) {
        if (values == null) {
            return Collections.emptySet();
        }
        String[] parts = StringUtils.explode(values, ',');
        Set<String> tmp = new LinkedHashSet<String>();
        for (String part : parts) {
            String trimmed = part.trim();
            if (trimmed.length() > 0) {
                tmp.add(trimmed.intern());
            }
        }
        return tmp;
    }

    public static Set<String> stringArrayToSet( final String [] array ) {
        if (array == null) {
            return Collections.emptySet();
        }
        Set<String> tmp = new LinkedHashSet<>();
        for (String part : array) {
            String trimmed = part.trim();
            if (trimmed.length() > 0) {
                tmp.add(trimmed.intern());
            }
        }
        return tmp;
    }
}