java.math

Class BigInteger

Implemented Interfaces:
Comparable<T>, Serializable

public class BigInteger
extends Number
implements Comparable<T>

Written using on-line Java Platform 1.2 API Specification, as well as "The Java Class Libraries", 2nd edition (Addison-Wesley, 1998) and "Applied Cryptography, Second Edition" by Bruce Schneier (Wiley, 1996). Based primarily on IntNum.java BitOps.java by Per Bothner (per@bothner.com) (found in Kawa 1.6.62).
See Also:
Serialized Form

Field Summary

static BigInteger
ONE
The constant one as a BigInteger.
static BigInteger
TEN
The constant ten as a BigInteger.
static BigInteger
ZERO
The constant zero as a BigInteger.

Constructor Summary

BigInteger(byte[] val)
BigInteger(int signum, byte[] magnitude)
BigInteger(int bitLength, int certainty, Random rnd)
BigInteger(int numBits, Random rnd)
BigInteger(String val)
BigInteger(String s, int radix)

Method Summary

BigInteger
abs()
BigInteger
add(BigInteger val)
BigInteger
and(BigInteger y)
Return the logical (bit-wise) "and" of two BigIntegers.
BigInteger
andNot(BigInteger val)
int
bitCount()
Count one bits in a BigInteger.
int
bitLength()
Calculates ceiling(log2(this <320 ?
BigInteger
clearBit(int n)
int
compareTo(BigInteger val)
BigInteger
divide(BigInteger val)
BigInteger[]
divideAndRemainder(BigInteger val)
double
doubleValue()
Return the value of this Number as a float.
boolean
equals(Object obj)
Determine whether this Object is semantically equal to another Object.
BigInteger
flipBit(int n)
float
floatValue()
Return the value of this Number as a float.
BigInteger
gcd(BigInteger y)
int
getLowestSetBit()
int
hashCode()
Get a value that represents this Object, as uniquely as possible within the confines of an int.
int
intValue()
Return the value of this Number as an int.
boolean
isProbablePrime(int certainty)
Returns true if this BigInteger is probably prime, false if it's definitely composite.
long
longValue()
Return the value of this Number as a long.
BigInteger
max(BigInteger val)
BigInteger
min(BigInteger val)
BigInteger
mod(BigInteger m)
BigInteger
modInverse(BigInteger y)
BigInteger
modPow(BigInteger exponent, BigInteger m)
BigInteger
multiply(BigInteger y)
BigInteger
negate()
BigInteger
not()
Return the logical (bit-wise) negation of a BigInteger.
BigInteger
or(BigInteger y)
Return the logical (bit-wise) "(inclusive) or" of two BigIntegers.
BigInteger
pow(int exponent)
Calculate the integral power of a BigInteger.
static BigInteger
probablePrime(int bitLength, Random rnd)
Return a BigInteger that is bitLength bits long with a probability <322^-100 of being composite.
BigInteger
remainder(BigInteger val)
BigInteger
setBit(int n)
BigInteger
shiftLeft(int n)
BigInteger
shiftRight(int n)
int
signum()
BigInteger
subtract(BigInteger val)
boolean
testBit(int n)
byte[]
toByteArray()
String
toString()
Convert this Object to a human-readable String.
String
toString(int radix)
static BigInteger
valueOf(long val)
Return a (possibly-shared) BigInteger with a given long value.
BigInteger
xor(BigInteger y)
Return the logical (bit-wise) "exclusive or" of two BigIntegers.

Methods inherited from class java.lang.Number

byteValue, doubleValue, floatValue, intValue, longValue, shortValue

Methods inherited from class java.lang.Object

clone, equals, extends Object> getClass, finalize, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Details

ONE

public static final BigInteger ONE
The constant one as a BigInteger.
Since:
1.2

TEN

public static final BigInteger TEN
The constant ten as a BigInteger.
Since:
1.5

ZERO

public static final BigInteger ZERO
The constant zero as a BigInteger.
Since:
1.2

Constructor Details

BigInteger

public BigInteger(byte[] val)

BigInteger

public BigInteger(int signum,
                  byte[] magnitude)

BigInteger

public BigInteger(int bitLength,
                  int certainty,
                  Random rnd)

BigInteger

public BigInteger(int numBits,
                  Random rnd)

BigInteger

public BigInteger(String val)

BigInteger

public BigInteger(String s,
                  int radix)

Method Details

abs

public BigInteger abs()

add

public BigInteger add(BigInteger val)

and

public BigInteger and(BigInteger y)
Return the logical (bit-wise) "and" of two BigIntegers.

andNot

public BigInteger andNot(BigInteger val)

bitCount

public int bitCount()
Count one bits in a BigInteger. If argument is negative, count zero bits instead.

bitLength

public int bitLength()
Calculates ceiling(log2(this <320 ? -this : this+1)) See Common Lisp: the Language, 2nd ed, p. 361.

clearBit

public BigInteger clearBit(int n)

compareTo

public int compareTo(BigInteger val)
Since:
1.2

divide

public BigInteger divide(BigInteger val)

divideAndRemainder

public BigInteger[] divideAndRemainder(BigInteger val)

doubleValue

public double doubleValue()
Return the value of this Number as a float.
Overrides:
doubleValue in interface Number
Returns:
the double value

equals

public boolean equals(Object obj)
Determine whether this Object is semantically equal to another Object.

There are some fairly strict requirements on this method which subclasses must follow:

  • It must be transitive. If a.equals(b) and b.equals(c), then a.equals(c) must be true as well.
  • It must be symmetric. a.equals(b) and b.equals(a) must have the same value.
  • It must be reflexive. a.equals(a) must always be true.
  • It must be consistent. Whichever value a.equals(b) returns on the first invocation must be the value returned on all later invocations.
  • a.equals(null) must be false.
  • It must be consistent with hashCode(). That is, a.equals(b) must imply a.hashCode() == b.hashCode(). The reverse is not true; two objects that are not equal may have the same hashcode, but that has the potential to harm hashing performance.

This is typically overridden to throw a ClassCastException if the argument is not comparable to the class performing the comparison, but that is not a requirement. It is legal for a.equals(b) to be true even though a.getClass() != b.getClass(). Also, it is typical to never cause a NullPointerException.

In general, the Collections API (java.util) use the equals method rather than the == operator to compare objects. However, IdentityHashMap is an exception to this rule, for its own good reasons.

The default implementation returns this == o.

Overrides:
equals in interface Object
Parameters:
obj - the Object to compare to
Returns:
whether this Object is semantically equal to another

flipBit

public BigInteger flipBit(int n)

floatValue

public float floatValue()
Return the value of this Number as a float.
Overrides:
floatValue in interface Number
Returns:
the float value

gcd

public BigInteger gcd(BigInteger y)

getLowestSetBit

public int getLowestSetBit()

hashCode

public int hashCode()
Get a value that represents this Object, as uniquely as possible within the confines of an int.

There are some requirements on this method which subclasses must follow:

  • Semantic equality implies identical hashcodes. In other words, if a.equals(b) is true, then a.hashCode() == b.hashCode() must be as well. However, the reverse is not necessarily true, and two objects may have the same hashcode without being equal.
  • It must be consistent. Whichever value o.hashCode() returns on the first invocation must be the value returned on all later invocations as long as the object exists. Notice, however, that the result of hashCode may change between separate executions of a Virtual Machine, because it is not invoked on the same object.

Notice that since hashCode is used in Hashtable and other hashing classes, a poor implementation will degrade the performance of hashing (so don't blindly implement it as returning a constant!). Also, if calculating the hash is time-consuming, a class may consider caching the results.

The default implementation returns System.identityHashCode(this)

Overrides:
hashCode in interface Object
Returns:
the hash code for this Object

intValue

public int intValue()
Return the value of this Number as an int.
Overrides:
intValue in interface Number
Returns:
the int value

isProbablePrime

public boolean isProbablePrime(int certainty)
Returns true if this BigInteger is probably prime, false if it's definitely composite. If certainty is <= 0, true is returned.
Parameters:
certainty - a measure of the uncertainty that the caller is willing to tolerate: if the call returns true the probability that this BigInteger is prime exceeds (1 - 1/2certainty). The execution time of this method is proportional to the value of this parameter.
Returns:
true if this BigInteger is probably prime, false if it's definitely composite.

longValue

public long longValue()
Return the value of this Number as a long.
Overrides:
longValue in interface Number
Returns:
the long value

max

public BigInteger max(BigInteger val)

min

public BigInteger min(BigInteger val)

mod

public BigInteger mod(BigInteger m)

modInverse

public BigInteger modInverse(BigInteger y)

modPow

public BigInteger modPow(BigInteger exponent,
                         BigInteger m)

multiply

public BigInteger multiply(BigInteger y)

negate

public BigInteger negate()

not

public BigInteger not()
Return the logical (bit-wise) negation of a BigInteger.

or

public BigInteger or(BigInteger y)
Return the logical (bit-wise) "(inclusive) or" of two BigIntegers.

pow

public BigInteger pow(int exponent)
Calculate the integral power of a BigInteger.
Parameters:
exponent - the exponent (must be non-negative)

probablePrime

public static BigInteger probablePrime(int bitLength,
                                       Random rnd)
Return a BigInteger that is bitLength bits long with a probability <322^-100 of being composite.
Parameters:
bitLength - length in bits of resulting number
rnd - random number generator to use
Throws:
ArithmeticException - if bitLength <322
Since:
1.4

remainder

public BigInteger remainder(BigInteger val)

setBit

public BigInteger setBit(int n)

shiftLeft

public BigInteger shiftLeft(int n)

shiftRight

public BigInteger shiftRight(int n)

signum

public int signum()

subtract

public BigInteger subtract(BigInteger val)

testBit

public boolean testBit(int n)

toByteArray

public byte[] toByteArray()

toString

public String toString()
Convert this Object to a human-readable String. There are no limits placed on how long this String should be or what it should contain. We suggest you make it as intuitive as possible to be able to place it into System.out.println() and such.

It is typical, but not required, to ensure that this method never completes abruptly with a RuntimeException.

This method will be called when performing string concatenation with this object. If the result is null, string concatenation will instead use "null".

The default implementation returns getClass().getName() + "@" + Integer.toHexString(hashCode()).

Overrides:
toString in interface Object
Returns:
the String representing this Object, which may be null

toString

public String toString(int radix)

valueOf

public static BigInteger valueOf(long val)
Return a (possibly-shared) BigInteger with a given long value.

xor

public BigInteger xor(BigInteger y)
Return the logical (bit-wise) "exclusive or" of two BigIntegers.

java.math.BigInteger -- Arbitary precision integers Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003, 2005, 2006, 2007, 2010 Free Software Foundation, Inc. This file is part of GNU Classpath. GNU Classpath is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2, or (at your option) any later version. GNU Classpath is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with GNU Classpath; see the file COPYING. If not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. Linking this library statically or dynamically with other modules is making a combined work based on this library. Thus, the terms and conditions of the GNU General Public License cover the whole combination. As a special exception, the copyright holders of this library give you permission to link this library with independent modules to produce an executable, regardless of the license terms of these independent modules, and to copy and distribute the resulting executable under terms of your choice, provided that you also meet, for each linked independent module, the terms and conditions of the license of that module. An independent module is a module which is not derived from or based on this library. If you modify this library, you may extend this exception to your version of the library, but you are not obligated to do so. If you do not wish to do so, delete this exception statement from your version.