public final class Fraction extends Number implements Comparable<Fraction>
Fraction
is a Number
implementation that
stores fractions accurately.
This class is immutable, and interoperable with most methods that accept
a Number
.
Note that this class is intended for common use cases, it is int based and thus suffers from various overflow issues. For a BigInteger based equivalent, please see the Commons Math BigFraction class.
Modifier and Type  Field and Description 

static Fraction 
FOUR_FIFTHS
Fraction representation of 4/5. 
static Fraction 
ONE
Fraction representation of 1. 
static Fraction 
ONE_FIFTH
Fraction representation of 1/5. 
static Fraction 
ONE_HALF
Fraction representation of 1/2. 
static Fraction 
ONE_QUARTER
Fraction representation of 1/4. 
static Fraction 
ONE_THIRD
Fraction representation of 1/3. 
static Fraction 
THREE_FIFTHS
Fraction representation of 3/5. 
static Fraction 
THREE_QUARTERS
Fraction representation of 3/4. 
static Fraction 
TWO_FIFTHS
Fraction representation of 2/5. 
static Fraction 
TWO_QUARTERS
Fraction representation of 2/4. 
static Fraction 
TWO_THIRDS
Fraction representation of 2/3. 
static Fraction 
ZERO
Fraction representation of 0. 
Modifier and Type  Method and Description 

Fraction 
abs()
Gets a fraction that is the positive equivalent of this one.

Fraction 
add(Fraction fraction)
Adds the value of this fraction to another, returning the result in reduced form.

int 
compareTo(Fraction other)
Compares this object to another based on size.

Fraction 
divideBy(Fraction fraction)
Divide the value of this fraction by another.

double 
doubleValue()
Gets the fraction as a
double . 
boolean 
equals(Object obj)
Compares this fraction to another object to test if they are equal.

float 
floatValue()
Gets the fraction as a
float . 
int 
getDenominator()
Gets the denominator part of the fraction.

static Fraction 
getFraction(double value)
Creates a
Fraction instance from a double value. 
static Fraction 
getFraction(int numerator,
int denominator)
Creates a
Fraction instance with the 2 parts
of a fraction Y/Z. 
static Fraction 
getFraction(int whole,
int numerator,
int denominator)
Creates a
Fraction instance with the 3 parts
of a fraction X Y/Z. 
static Fraction 
getFraction(String str)
Creates a Fraction from a
String . 
int 
getNumerator()
Gets the numerator part of the fraction.

int 
getProperNumerator()
Gets the proper numerator, always positive.

int 
getProperWhole()
Gets the proper whole part of the fraction.

static Fraction 
getReducedFraction(int numerator,
int denominator)
Creates a reduced
Fraction instance with the 2 parts
of a fraction Y/Z. 
int 
hashCode()
Gets a hashCode for the fraction.

int 
intValue()
Gets the fraction as an
int . 
Fraction 
invert()
Gets a fraction that is the inverse (1/fraction) of this one.

long 
longValue()
Gets the fraction as a
long . 
Fraction 
multiplyBy(Fraction fraction)
Multiplies the value of this fraction by another, returning the
result in reduced form.

Fraction 
negate()
Gets a fraction that is the negative (fraction) of this one.

Fraction 
pow(int power)
Gets a fraction that is raised to the passed in power.

Fraction 
reduce()
Reduce the fraction to the smallest values for the numerator and
denominator, returning the result.

Fraction 
subtract(Fraction fraction)
Subtracts the value of another fraction from the value of this one,
returning the result in reduced form.

String 
toProperString()
Gets the fraction as a proper
String in the format X Y/Z. 
String 
toString()
Gets the fraction as a
String . 
byteValue, shortValue
public static final Fraction TWO_THIRDS
Fraction
representation of 2/3.public static final Fraction ONE_QUARTER
Fraction
representation of 1/4.public static final Fraction TWO_QUARTERS
Fraction
representation of 2/4.public static final Fraction THREE_QUARTERS
Fraction
representation of 3/4.public static final Fraction TWO_FIFTHS
Fraction
representation of 2/5.public static final Fraction THREE_FIFTHS
Fraction
representation of 3/5.public static final Fraction FOUR_FIFTHS
Fraction
representation of 4/5.public static Fraction getFraction(int numerator, int denominator)
Creates a Fraction
instance with the 2 parts
of a fraction Y/Z.
Any negative signs are resolved to be on the numerator.
numerator
 the numerator, for example the three in 'three sevenths'denominator
 the denominator, for example the seven in 'three sevenths'ArithmeticException
 if the denominator is zero
or the denominator is negative
and the numerator is Integer#MIN_VALUE
public static Fraction getFraction(int whole, int numerator, int denominator)
Creates a Fraction
instance with the 3 parts
of a fraction X Y/Z.
The negative sign must be passed in on the whole number part.
whole
 the whole number, for example the one in 'one and three sevenths'numerator
 the numerator, for example the three in 'one and three sevenths'denominator
 the denominator, for example the seven in 'one and three sevenths'ArithmeticException
 if the denominator is zero
ArithmeticException
 if the denominator is negativeArithmeticException
 if the numerator is negativeArithmeticException
 if the resulting numerator exceeds
Integer.MAX_VALUE
public static Fraction getReducedFraction(int numerator, int denominator)
Creates a reduced Fraction
instance with the 2 parts
of a fraction Y/Z.
For example, if the input parameters represent 2/4, then the created fraction will be 1/2.
Any negative signs are resolved to be on the numerator.
numerator
 the numerator, for example the three in 'three sevenths'denominator
 the denominator, for example the seven in 'three sevenths'ArithmeticException
 if the denominator is zero
public static Fraction getFraction(double value)
Creates a Fraction
instance from a double
value.
This method uses the continued fraction algorithm, computing a maximum of 25 convergents and bounding the denominator by 10,000.
value
 the double value to convertArithmeticException
 if value > Integer.MAX_VALUE
or value = NaN
ArithmeticException
 if the calculated denominator is zero
ArithmeticException
 if the the algorithm does not convergepublic static Fraction getFraction(String str)
Creates a Fraction from a String
.
The formats accepted are:
double
String containing a dotand a .
str
 the string to parse, must not be null
Fraction
instanceIllegalArgumentException
 if the string is null
NumberFormatException
 if the number format is invalidpublic int getNumerator()
Gets the numerator part of the fraction.
This method may return a value greater than the denominator, an improper fraction, such as the seven in 7/4.
public int getDenominator()
Gets the denominator part of the fraction.
public int getProperNumerator()
Gets the proper numerator, always positive.
An improper fraction 7/4 can be resolved into a proper one, 1 3/4. This method returns the 3 from the proper fraction.
If the fraction is negative such as 7/4, it can be resolved into 1 3/4, so this method returns the positive proper numerator, 3.
public int getProperWhole()
Gets the proper whole part of the fraction.
An improper fraction 7/4 can be resolved into a proper one, 1 3/4. This method returns the 1 from the proper fraction.
If the fraction is negative such as 7/4, it can be resolved into 1 3/4, so this method returns the positive whole part 1.
public int intValue()
Gets the fraction as an int
. This returns the whole number
part of the fraction.
public long longValue()
Gets the fraction as a long
. This returns the whole number
part of the fraction.
public float floatValue()
Gets the fraction as a float
. This calculates the fraction
as the numerator divided by denominator.
floatValue
in class Number
float
public double doubleValue()
Gets the fraction as a double
. This calculates the fraction
as the numerator divided by denominator.
doubleValue
in class Number
double
public Fraction reduce()
Reduce the fraction to the smallest values for the numerator and denominator, returning the result.
For example, if this fraction represents 2/4, then the result will be 1/2.
public Fraction invert()
Gets a fraction that is the inverse (1/fraction) of this one.
The returned fraction is not reduced.
ArithmeticException
 if the fraction represents zero.public Fraction negate()
Gets a fraction that is the negative (fraction) of this one.
The returned fraction is not reduced.
public Fraction abs()
Gets a fraction that is the positive equivalent of this one.
More precisely: (fraction >= 0 ? this : fraction)
The returned fraction is not reduced.
this
if it is positive, or a new positive fraction
instance with the opposite signed numeratorpublic Fraction pow(int power)
Gets a fraction that is raised to the passed in power.
The returned fraction is in reduced form.
power
 the power to raise the fraction tothis
if the power is one, ONE
if the power
is zero (even if the fraction equals ZERO) or a new fraction instance
raised to the appropriate powerArithmeticException
 if the resulting numerator or denominator exceeds
Integer.MAX_VALUE
public Fraction add(Fraction fraction)
Adds the value of this fraction to another, returning the result in reduced form. The algorithm follows Knuth, 4.5.1.
fraction
 the fraction to add, must not be null
Fraction
instance with the resulting valuesIllegalArgumentException
 if the fraction is null
ArithmeticException
 if the resulting numerator or denominator exceeds
Integer.MAX_VALUE
public Fraction subtract(Fraction fraction)
Subtracts the value of another fraction from the value of this one, returning the result in reduced form.
fraction
 the fraction to subtract, must not be null
Fraction
instance with the resulting valuesIllegalArgumentException
 if the fraction is null
ArithmeticException
 if the resulting numerator or denominator
cannot be represented in an int
.public Fraction multiplyBy(Fraction fraction)
Multiplies the value of this fraction by another, returning the result in reduced form.
fraction
 the fraction to multiply by, must not be null
Fraction
instance with the resulting valuesIllegalArgumentException
 if the fraction is null
ArithmeticException
 if the resulting numerator or denominator exceeds
Integer.MAX_VALUE
public Fraction divideBy(Fraction fraction)
Divide the value of this fraction by another.
fraction
 the fraction to divide by, must not be null
Fraction
instance with the resulting valuesIllegalArgumentException
 if the fraction is null
ArithmeticException
 if the fraction to divide by is zeroArithmeticException
 if the resulting numerator or denominator exceeds
Integer.MAX_VALUE
public boolean equals(Object obj)
Compares this fraction to another object to test if they are equal.
.To be equal, both values must be equal. Thus 2/4 is not equal to 1/2.
public int hashCode()
Gets a hashCode for the fraction.
public int compareTo(Fraction other)
Compares this object to another based on size.
Note: this class has a natural ordering that is inconsistent with equals, because, for example, equals treats 1/2 and 2/4 as different, whereas compareTo treats them as equal.
compareTo
in interface Comparable<Fraction>
other
 the object to compare toClassCastException
 if the object is not a Fraction
NullPointerException
 if the object is null
public String toString()
Gets the fraction as a String
.
The format used is 'numerator/denominator' always.
public String toProperString()
Gets the fraction as a proper String
in the format X Y/Z.
The format used in 'wholeNumber numerator/denominator'. If the whole number is zero it will be omitted. If the numerator is zero, only the whole number is returned.
String
form of the fractionCopyright © 2001–2014 The Apache Software Foundation. All rights reserved.