net.derquinse.common.test.RandomSupport.java Source code

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Here is the source code for net.derquinse.common.test.RandomSupport.java

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/*
 * Copyright (C) the original author or authors.
 *
 * 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 net.derquinse.common.test;

import java.security.SecureRandom;

import com.google.common.io.ByteSource;

/**
 * Randomness support class for tests.
 * @author Andres Rodriguez
 */
public final class RandomSupport {
    private static final SecureRandom RANDOM = new SecureRandom();

    /** Not instantiable. */
    private RandomSupport() {
        throw new AssertionError();
    }

    /**
     * Returns a pseudorandom, uniformly distributed {@code int}.
     */
    public static int nextInt() {
        return RANDOM.nextInt();
    }

    /**
     * Returns a pseudorandom, uniformly distributed {@code int} value between 0 (inclusive) and the
     * specified value (exclusive).
     */
    public static int nextInt(int max) {
        return RANDOM.nextInt(max);
    }

    /**
     * Returns a pseudorandom, uniformly distributed {@code int} value between the {@code min}
     * argument (inclusive) and the {@code max} argument (exclusive).
     */
    public static int nextInt(int min, int max) {
        return min + nextInt(max - min);
    }

    /**
     * Generates a user-specified number of random bytes.
     */
    public static byte[] getBytes(int amount) {
        byte[] data = new byte[amount];
        RANDOM.nextBytes(data);
        return data;
    }

    /**
     * Generates a user-specified number of random bytes, returning them as a byte source.
     */
    public static ByteSource getSource(int amount) {
        return ByteSource.wrap(getBytes(amount));
    }
}