org.uncommons.maths.number
Class Rational

java.lang.Object
  java.lang.Number
      org.uncommons.maths.number.Rational

All Implemented Interfaces:

Serializable, Comparable<Rational>

public final class Rational
extends Number
implements Comparable<Rational>

Immutable value object for representing a rational number (or vulgar fraction). Instances of this class provide a way to perform arithmetic on fractional values without loss of precision. This implementation automatically simplifies fractions (3/6 is stored as 1/2). The implementation also requires that the denominator is positive. The numerator may be negative.

Since:

1.2

Author:

Daniel Dyer

See Also:

Serialized Form

Field Summary

static Rational	HALF Convenient constant representing a value of a half (1/2 as a rational).
static Rational	ONE Convenient constant representing a value of one (1/1 as a rational).
static Rational	QUARTER Convenient constant representing a value of a quarter (1/4 as a rational).
static Rational	THIRD Convenient constant representing a value of a third (1/3 as a rational).
static Rational	THREE_QUARTERS Convenient constant representing a value of three quarters (3/4 as a rational).
static Rational	TWO_THIRDS Convenient constant representing a value of two thirds (2/3 as a rational).
static Rational	ZERO Convenient constant representing a value of zero (0/1 as a rational).

Constructor Summary

Rational(BigDecimal value)
Creates a rational value equivalent to the specified decimal value.

Rational(long value)
Creates a rational value equivalent to the specified integer value.

Rational(long numerator, long denominator)
Creates a vulgar fraction with the specified numerator and denominator.

Method Summary

Rational	add(Rational value) Add the specified value to this value and return the result as a new object (also a rational).
int	compareTo(Rational other) Compares this value with the specified object for order.
Rational	divide(Rational value) Divide this rational by the specified value and return the result as a new object (also a Rational).
double	doubleValue() Returns the result of dividing the numerator by the denominator.
boolean	equals(Object other) Determines whether this rational value is equal to some other object.
float	floatValue() Returns the result of dividing the numerator by the denominator.
long	getDenominator() Returns the denominator (divisor) of the fraction.
long	getNumerator() Returns the numerator of the fraction.
int	hashCode() Over-ridden to be consistent with equals(Object).
int	intValue() Returns the integer equivalent of this rational number.
long	longValue() Returns the integer equivalent of this rational number as a long.
Rational	multiply(Rational value) Multiply this rational by the specified value and return the result as a new object (also a Rational).
Rational	subtract(Rational value) Subtract the specified value from this value and return the result as a new object (also a rational).
String	toString() Returns a String representation of the rational number, expressed as a vulgar fraction (i.e.

Methods inherited from class java.lang.Number

byteValue, shortValue

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

ZERO

public static final Rational ZERO

Convenient constant representing a value of zero (0/1 as a rational).

QUARTER

public static final Rational QUARTER

Convenient constant representing a value of a quarter (1/4 as a rational).

THIRD

public static final Rational THIRD

Convenient constant representing a value of a third (1/3 as a rational).

HALF

public static final Rational HALF

Convenient constant representing a value of a half (1/2 as a rational).

TWO_THIRDS

public static final Rational TWO_THIRDS

Convenient constant representing a value of two thirds (2/3 as a rational).

THREE_QUARTERS

public static final Rational THREE_QUARTERS

Convenient constant representing a value of three quarters (3/4 as a rational).

ONE

public static final Rational ONE

Convenient constant representing a value of one (1/1 as a rational).

Constructor Detail

Rational

public Rational(long numerator,
                long denominator)

Creates a vulgar fraction with the specified numerator and denominator.

Parameters:

numerator - The fraction's numerator (may be negative).

denominator - The fraction's denominator (must be greater than or equal to 1).

Rational

public Rational(long value)

Creates a rational value equivalent to the specified integer value.

Parameters:

value - The value of this rational as an integer.

Rational

public Rational(BigDecimal value)

Creates a rational value equivalent to the specified decimal value.

Parameters:

value - The value of this rational as a fractional decimal.

Throws:

ArithmeticException - If the BigDecimal value is too large to be represented as a Rational.

Method Detail

getNumerator

public long getNumerator()

Returns the numerator of the fraction.

Returns:

The numerator.

getDenominator

public long getDenominator()

Returns the denominator (divisor) of the fraction.

Returns:

The denominator.

add

public Rational add(Rational value)

Add the specified value to this value and return the result as a new object (also a rational). If the two values have different denominators, they will first be converted so that they have common denominators.

Parameters:

value - The value to add to this rational.

Returns:

A new rational value that is the sum of this value and the specified value.

subtract

public Rational subtract(Rational value)

Subtract the specified value from this value and return the result as a new object (also a rational). If the two values have different denominators, they will first be converted so that they have common denominators.

Parameters:

value - The value to subtract from this rational.

Returns:

A new rational value that is the result of subtracting the specified value from this value.

multiply

public Rational multiply(Rational value)

Multiply this rational by the specified value and return the result as a new object (also a Rational).

Parameters:

value - The amount to multiply by.

Returns:

A new rational value that is the result of multiplying this value by the specified value.

divide

public Rational divide(Rational value)

Divide this rational by the specified value and return the result as a new object (also a Rational).

Parameters:

value - The amount to divide by.

Returns:

A new rational value that is the result of dividing this value by the specified value.

intValue

public int intValue()

Returns the integer equivalent of this rational number. If there is no exact integer representation, it returns the closest integer that is lower than the rational value (effectively the truncated version of calling doubleValue()).

Specified by:

intValue in class Number

Returns:

The (truncated) integer value of this rational.

longValue

public long longValue()

Returns the integer equivalent of this rational number as a long. If there is no exact integer representation, it returns the closest long that is lower than the rational value (effectively the truncated version of calling doubleValue()).

Specified by:

longValue in class Number

Returns:

The (truncated) long value of this rational.

floatValue

public float floatValue()

Returns the result of dividing the numerator by the denominator. Will result in a loss of precision for fractions that have no exact float representation.

Specified by:

floatValue in class Number

Returns:

The closest double-precision floating point equivalent of the fraction represented by this object.

doubleValue

public double doubleValue()

Returns the result of dividing the numerator by the denominator. Will result in a loss of precision for fractions that have no exact double representation.

Specified by:

doubleValue in class Number

Returns:

The closest double-precision floating point equivalent of the fraction represented by this object.

equals

public boolean equals(Object other)

Determines whether this rational value is equal to some other object. To be considered equal the other object must also be a Rational object with an indentical numerator and denominator.

Overrides:

equals in class Object

Parameters:

other - The object to compare against.

Returns:

True if the objects are equal, false otherwise.

hashCode

public int hashCode()

Over-ridden to be consistent with equals(Object).

Overrides:

hashCode in class Object

Returns:

The hash code value.

toString

public String toString()

Returns a String representation of the rational number, expressed as a vulgar fraction (i.e. 1 and 1/3 is shown as 4/3). If the rational is equal to an integer, the value is simply displayed as that integer with no fractional part (i.e. 2/1 is shown as 2).

Overrides:

toString in class Object

Returns:

A string representation of this rational value.

compareTo

public int compareTo(Rational other)

Compares this value with the specified object for order. Returns a negative integer, zero, or a positive integer as this value is less than, equal to, or greater than the specified value.

Specified by:

compareTo in interface Comparable<Rational>

Parameters:

other - Another Rational value.

Returns:

A negative integer, zero, or a positive integer as this value is less than, equal to, or greater than the specified value.