RandomString.java

/*
 * Copyright 2011-16 Fraunhofer ISE
 *
 * This file is part of OpenMUC.
 * For more information visit http://www.openmuc.org
 *
 * OpenMUC 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 3 of the License, or
 * (at your option) any later version.
 *
 * OpenMUC is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with OpenMUC.  If not, see <http://www.gnu.org/licenses/>.
 *
 */

package org.openmuc.framework.core.datamanager;

import java.util.Random;

public final class RandomString {

    private static final char[] symbols = new char[36];

    static {
        for (int idx = 0; idx < 10; ++idx) {
            symbols[idx] = (char) ('0' + idx);
        }
        for (int idx = 10; idx < 36; ++idx) {
            symbols[idx] = (char) ('a' + idx - 10);
        }
    }

    private final Random random = new Random();

    private final char[] buf;

    public RandomString(int length) {
        if (length < 1) {
            throw new IllegalArgumentException("length < 1: " + length);
        }
        buf = new char[length];
    }

    public String nextString() {
        for (int idx = 0; idx < buf.length; ++idx) {
            buf[idx] = symbols[random.nextInt(symbols.length)];
        }
        return new String(buf);
    }

}