001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.apache.commons.text;
018
019/**
020 * TextRandomProvider implementations are used by {@link RandomStringGenerator}
021 * as a source of randomness.  It is highly recommended that the
022 * <a href="https://commons.apache.org/proper/commons-rng/">Apache Commons RNG</a>
023 * library be used to provide the random number generation.
024 *
025 * <p>
026 * When using Java 8 or later, TextRandomProvider is a functional interface and
027 * need not be explicitly implemented.  For example:
028 * </p>
029 * <pre>
030 * {@code
031 * UniformRandomProvider rng = RandomSource.create(...);
032 * RandomStringGenerator gen = RandomStringGenerator.builder()
033 *     .usingRandom(rng::nextInt)
034 *     // additional builder calls as needed
035 *     .build();
036 * }
037 * </pre>
038 * @since 1.1
039 */
040public interface TextRandomProvider {
041
042    /**
043     * Generates an int value between 0 (inclusive) and the specified value
044     * (exclusive).
045     * @param max  Bound on the random number to be returned. Must be positive.
046     * @return a random int value between 0 (inclusive) and n (exclusive).
047     */
048    int nextInt(int max);
049}