com.alibaba.nacos.common.utils.RandomUtils Maven / Gradle / Ivy
/*
* Copyright 1999-2018 Alibaba Group Holding Ltd.
*
* 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 com.alibaba.nacos.common.utils;
import java.util.Random;
/**
* Random utils.
*
* @author zzq
*/
public class RandomUtils {
private RandomUtils() {
}
/**
* Random Object for random method.
*/
private static final Random RANDOM = new Random();
/**
* Returns a random long within the specified range.
*
* @param startInclusive the smallest value that can be returned, must be non-negative
* @param endExclusive the upper bound (not included)
* @return the random long
* @throws IllegalArgumentException if startInclusive or endExclusive illegal
*/
public static long nextLong(final long startInclusive, final long endExclusive) {
checkParameters(startInclusive, endExclusive);
long diff = endExclusive - startInclusive;
if (diff == 0) {
return startInclusive;
}
return (long) (startInclusive + (diff * RANDOM.nextDouble()));
}
/**
* Returns a random integer within the specified range.
*
* @param startInclusive lower limit, must be non-negative
* @param endExclusive the upper bound (not included)
* @return the random integer
* @throws IllegalArgumentException if startInclusive or endExclusive illegal
*/
public static int nextInt(final int startInclusive, final int endExclusive) {
checkParameters(startInclusive, endExclusive);
int diff = endExclusive - startInclusive;
if (diff == 0) {
return startInclusive;
}
return startInclusive + RANDOM.nextInt(diff);
}
/**
* Check input parameters.
*
* @param startInclusive lower limit, must be non-negative
* @param endExclusive the upper bound (not included)
*/
private static void checkParameters(final long startInclusive, final long endExclusive) {
if (endExclusive < startInclusive) {
throw new IllegalArgumentException("startInclusive must be less than or equal to the endExclusive.");
}
if (startInclusive < 0) {
throw new IllegalArgumentException("Both parameters must be non-negative");
}
}
}