su.litvak.chromecast.api.v2.RandomString Maven / Gradle / Ivy

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/*
 * Copyright 2014 Vitaly Litvak ([email protected])
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package su.litvak.chromecast.api.v2;

import java.util.Random;

/**
 * Utility class for generating random strings of human-readable characters.
 */
class RandomString {
    private static char[] symbols;

    static {
        StringBuilder tmp = new StringBuilder();
        for (char ch = '0'; ch <= '9'; ++ch) {
            tmp.append(ch);
        }
        for (char ch = 'a'; ch <= 'z'; ++ch) {
            tmp.append(ch);
        }
        symbols = tmp.toString().toCharArray();
    }

    private final Random random = new Random();

    private final char[] buf;

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

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