rice.p2p.util
Class MathUtils

java.lang.Object
  rice.p2p.util.MathUtils

public class MathUtils

extends java.lang.Object

This class contains a large number of static methods for performing math operations.

Version:

$Id: MathUtils.java,v 1.4 2005/05/24 21:27:56 jstewart Exp $

Author:

amislove

Field Summary

static char[]

HEX_ARRAY The array used for conversion to hexidecimal

Method Summary

static int	byteArrayToInt(byte[] input) Utility method for converting a byte[] into a int
static long	byteArrayToLong(byte[] input) Utility method for converting a byte[] into a long
static byte[]	intToByteArray(int input) Utility method for converting a int into a byte[]
static void	intToByteArray(int input, byte[] output, int offset) Utility method for converting a int into a byte[]
static byte[]	longToByteArray(long input) Utility method for converting a long into a byte[]
static void	longToByteArray(long input, byte[] output, int offset) Utility method for converting a long into a byte[]
static int	mod(int a, int b) Utility which does *proper* modding, where the result is guaranteed to be positive.
static byte[]	randomBytes(int len) Method which returns a specified number of random bytes
static int	randomInt() Method which returns a random int
static java.lang.String	toHex(byte[] text) Utility method which converts a byte[] to a hexidecimal string of characters, in lower case
static byte[]	xor(byte[] a, byte[] b) Utility method which xors two given byte arrays, of equal length, and returns the results

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

HEX_ARRAY

public static final char[] HEX_ARRAY

The array used for conversion to hexidecimal

Method Detail

mod

public static int mod(int a,
                      int b)

Utility which does *proper* modding, where the result is guaranteed to be positive.

Parameters:

a - The modee

b - The value to mod by

Returns:

The result

xor

public static byte[] xor(byte[] a,
                         byte[] b)

Utility method which xors two given byte arrays, of equal length, and returns the results

Parameters:

a - The first array

b - The second array

Returns:

A new byte array, xored

randomBytes

public static byte[] randomBytes(int len)

Method which returns a specified number of random bytes

Parameters:

len - The number of random bytes to generate

Returns:

DESCRIBE THE RETURN VALUE

randomInt

public static int randomInt()

Method which returns a random int

Returns:

DESCRIBE THE RETURN VALUE

toHex

public static java.lang.String toHex(byte[] text)

Utility method which converts a byte[] to a hexidecimal string of characters, in lower case

Parameters:

text - The array to convert

Returns:

A string representation

intToByteArray

public static byte[] intToByteArray(int input)

Utility method for converting a int into a byte[]

Parameters:

input - The log to convert

Returns:

a byte[] representation

intToByteArray

public static void intToByteArray(int input,
                                  byte[] output,
                                  int offset)

Utility method for converting a int into a byte[]

Parameters:

input - The log to convert

output - DESCRIBE THE PARAMETER

offset - DESCRIBE THE PARAMETER

byteArrayToInt

public static int byteArrayToInt(byte[] input)

Utility method for converting a byte[] into a int

Parameters:

input - The byte[] to convert

Returns:

a int representation

longToByteArray

public static byte[] longToByteArray(long input)

Utility method for converting a long into a byte[]

Parameters:

input - The log to convert

Returns:

a byte[] representation

longToByteArray

public static void longToByteArray(long input,
                                   byte[] output,
                                   int offset)

Utility method for converting a long into a byte[]

Parameters:

input - The log to convert

output - DESCRIBE THE PARAMETER

offset - DESCRIBE THE PARAMETER

byteArrayToLong

public static long byteArrayToLong(byte[] input)

Utility method for converting a byte[] into a long

Parameters:

input - The byte[] to convert

Returns:

a long representation