/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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 org.apache.commons.lang3;
import java.util.
Random;
/**
* <p>Utility library that supplements the standard {@link Random} class.</p>
*
* @since 3.3
*/
public class
RandomUtils {
/**
* Random object used by random method. This has to be not local to the
* random method so as to not return the same value in the same millisecond.
*/
private static final
Random RANDOM = new
Random();
/**
* <p>
* {@code RandomUtils} instances should NOT be constructed in standard
* programming. Instead, the class should be used as
* {@code RandomUtils.nextBytes(5);}.
* </p>
*
* <p>
* This constructor is public to permit tools that require a JavaBean
* instance to operate.
* </p>
*/
public
RandomUtils() {
super();
}
/**
* <p>
* Returns a random boolean value
* </p>
*
* @return the random boolean
* @since 3.5
*/
public static boolean
nextBoolean() {
return
RANDOM.
nextBoolean();
}
/**
* <p>
* Creates an array of random bytes.
* </p>
*
* @param count
* the size of the returned array
* @return the random byte array
* @throws IllegalArgumentException if {@code count} is negative
*/
public static byte[]
nextBytes(final int
count) {
Validate.
isTrue(
count >= 0, "Count cannot be negative.");
final byte[]
result = new byte[
count];
RANDOM.
nextBytes(
result);
return
result;
}
/**
* <p>
* Returns a random integer within the specified range.
* </p>
*
* @param startInclusive
* the smallest value that can be returned, must be non-negative
* @param endExclusive
* the upper bound (not included)
* @throws IllegalArgumentException
* if {@code startInclusive > endExclusive} or if
* {@code startInclusive} is negative
* @return the random integer
*/
public static int
nextInt(final int
startInclusive, final int
endExclusive) {
Validate.
isTrue(
endExclusive >=
startInclusive,
"Start value must be smaller or equal to end value.");
Validate.
isTrue(
startInclusive >= 0, "Both range values must be non-negative.");
if (
startInclusive ==
endExclusive) {
return
startInclusive;
}
return
startInclusive +
RANDOM.
nextInt(
endExclusive -
startInclusive);
}
/**
* <p> Returns a random int within 0 - Integer.MAX_VALUE </p>
*
* @return the random integer
* @see #nextInt(int, int)
* @since 3.5
*/
public static int
nextInt() {
return
nextInt(0,
Integer.
MAX_VALUE);
}
/**
* <p>
* Returns a random long within the specified range.
* </p>
*
* @param startInclusive
* the smallest value that can be returned, must be non-negative
* @param endExclusive
* the upper bound (not included)
* @throws IllegalArgumentException
* if {@code startInclusive > endExclusive} or if
* {@code startInclusive} is negative
* @return the random long
*/
public static long
nextLong(final long
startInclusive, final long
endExclusive) {
Validate.
isTrue(
endExclusive >=
startInclusive,
"Start value must be smaller or equal to end value.");
Validate.
isTrue(
startInclusive >= 0, "Both range values must be non-negative.");
if (
startInclusive ==
endExclusive) {
return
startInclusive;
}
return (long)
nextDouble(
startInclusive,
endExclusive);
}
/**
* <p> Returns a random long within 0 - Long.MAX_VALUE </p>
*
* @return the random long
* @see #nextLong(long, long)
* @since 3.5
*/
public static long
nextLong() {
return
nextLong(0,
Long.
MAX_VALUE);
}
/**
* <p>
* Returns a random double within the specified range.
* </p>
*
* @param startInclusive
* the smallest value that can be returned, must be non-negative
* @param endInclusive
* the upper bound (included)
* @throws IllegalArgumentException
* if {@code startInclusive > endInclusive} or if
* {@code startInclusive} is negative
* @return the random double
*/
public static double
nextDouble(final double
startInclusive, final double
endInclusive) {
Validate.
isTrue(
endInclusive >=
startInclusive,
"Start value must be smaller or equal to end value.");
Validate.
isTrue(
startInclusive >= 0, "Both range values must be non-negative.");
if (
startInclusive ==
endInclusive) {
return
startInclusive;
}
return
startInclusive + ((
endInclusive -
startInclusive) *
RANDOM.
nextDouble());
}
/**
* <p> Returns a random double within 0 - Double.MAX_VALUE </p>
*
* @return the random double
* @see #nextDouble(double, double)
* @since 3.5
*/
public static double
nextDouble() {
return
nextDouble(0,
Double.
MAX_VALUE);
}
/**
* <p>
* Returns a random float within the specified range.
* </p>
*
* @param startInclusive
* the smallest value that can be returned, must be non-negative
* @param endInclusive
* the upper bound (included)
* @throws IllegalArgumentException
* if {@code startInclusive > endInclusive} or if
* {@code startInclusive} is negative
* @return the random float
*/
public static float
nextFloat(final float
startInclusive, final float
endInclusive) {
Validate.
isTrue(
endInclusive >=
startInclusive,
"Start value must be smaller or equal to end value.");
Validate.
isTrue(
startInclusive >= 0, "Both range values must be non-negative.");
if (
startInclusive ==
endInclusive) {
return
startInclusive;
}
return
startInclusive + ((
endInclusive -
startInclusive) *
RANDOM.
nextFloat());
}
/**
* <p> Returns a random float within 0 - Float.MAX_VALUE </p>
*
* @return the random float
* @see #nextFloat()
* @since 3.5
*/
public static float
nextFloat() {
return
nextFloat(0,
Float.
MAX_VALUE);
}
}