com.jaemon.dingtalk.utils.JVMRandom Maven / Gradle / Ivy
/*
* Copyright 2015-2020 Jaemon([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 com.jaemon.dingtalk.utils;
import java.util.Random;
/**
* JVMRandom is a wrapper that supports all possible
* Random methods via the {@link java.lang.Math#random()} method
* and its system-wide {@link Random} object.
*
* @since 2.0
* @version $Id: JVMRandom.java 471626 2006-11-06 04:02:09Z bayard $
*/
public final class JVMRandom extends Random {
/**
* Required for serialization support.
*
* @see java.io.Serializable
*/
private static final long serialVersionUID = 1L;
/**
* Ensures that only the constructor can call reseed.
*/
private boolean constructed = false;
/**
* Constructs a new instance.
*/
public JVMRandom() {
this.constructed = true;
}
/**
* Unsupported in 2.0.
*
* @param seed ignored
* @throws UnsupportedOperationException unsupportedOperationException
*/
@Override
public synchronized void setSeed(long seed) {
if (this.constructed) {
throw new UnsupportedOperationException();
}
}
/**
* Unsupported in 2.0.
*
* @return Nothing, this method always throws an UnsupportedOperationException.
* @throws UnsupportedOperationException unsupportedOperationException
*/
@Override
public synchronized double nextGaussian() {
throw new UnsupportedOperationException();
}
/**
* Unsupported in 2.0.
*
* @param byteArray ignored
* @throws UnsupportedOperationException unsupportedOperationException
*/
@Override
public void nextBytes(byte[] byteArray) {
throw new UnsupportedOperationException();
}
/**
* Returns the next pseudorandom, uniformly distributed int value
* from the Math.random() sequence.
*
* @return the random int
*/
@Override
public int nextInt() {
return nextInt(Integer.MAX_VALUE);
}
/**
* Returns a pseudorandom, uniformly distributed int value between
* 0 (inclusive) and the specified value (exclusive), from
* the Math.random() sequence.
*
* @param n the specified exclusive max-value
* @return the random int
* @throws IllegalArgumentException when n <= 0
*/
@Override
public int nextInt(int n) {
if (n <= 0) {
throw new IllegalArgumentException(
"Upper bound for nextInt must be positive"
);
}
return (int)(Math.random() * n);
}
/**
* Returns the next pseudorandom, uniformly distributed long value
* from the Math.random() sequence.
* @return the random long
*/
@Override
public long nextLong() {
// possible loss of precision?
return nextLong(Long.MAX_VALUE);
}
/**
* Returns a pseudorandom, uniformly distributed long value between
* 0 (inclusive) and the specified value (exclusive), from
* the Math.random() sequence.
*
* @param n the specified exclusive max-value
* @return the random long
* @throws IllegalArgumentException when n <= 0
*/
public static long nextLong(long n) {
if (n <= 0) {
throw new IllegalArgumentException(
"Upper bound for nextInt must be positive"
);
}
return (long)(Math.random() * n);
}
/**
* Returns the next pseudorandom, uniformly distributed boolean value
* from the Math.random() sequence.
*
* @return the random boolean
*/
@Override
public boolean nextBoolean() {
return Math.random() > 0.5;
}
/**
* Returns the next pseudorandom, uniformly distributed float value
* between 0.0 and 1.0 from the Math.random()
* sequence.
*
* @return the random float
*/
@Override
public float nextFloat() {
return (float)Math.random();
}
/**
* Synonymous to the Math.random() call.
*
* @return the random double
*/
@Override
public double nextDouble() {
return Math.random();
}
}