Class Fraction

Method Details

• getFraction

  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.

  Parameters:

  numerator - the numerator, for example the three in 'three sevenths'

  denominator - the denominator, for example the seven in 'three sevenths'

  Returns:

  a new fraction instance

  Throws:

  ArithmeticException - if the denomiator is zero

• getFraction

  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.

  Parameters:

  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'

  Returns:

  a new fraction instance

  Throws:

  ArithmeticException - if the denomiator is zero

  ArithmeticException - if the denominator is negative

  ArithmeticException - if the numerator is negative

  ArithmeticException - if the resulting numerator exceeds Integer.MAX_VALUE

• getReducedFraction

  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.

  Parameters:

  numerator - the numerator, for example the three in 'three sevenths'

  denominator - the denominator, for example the seven in 'three sevenths'

  Returns:

  a new fraction instance, with the numerator and denominator reduced

  Throws:

  ArithmeticException - if the denominator is zero

• getFraction

  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.

  Parameters:

  value - the double value to convert

  Returns:

  a new fraction instance that is close to the value

  Throws:

  ArithmeticException - if |value| > Integer.MAX_VALUE or value = NaN

  ArithmeticException - if the calculated denominator is zero

  ArithmeticException - if the the algorithm does not converge

• getFraction

  public static Fraction getFraction(String str)

  Creates a Fraction from a String.

  The formats accepted are:

  1. double String containing a dot
  2. 'X Y/Z'
  3. 'Y/Z'
  4. 'X' (a simple whole number)

  and a .

  Parameters:

  str - the string to parse, must not be null

  Returns:

  the new Fraction instance

  Throws:

  IllegalArgumentException - if the string is null

  NumberFormatException - if the number format is invalid

• getNumerator

  public 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.

  Returns:

  the numerator fraction part

• getDenominator

  public int getDenominator()

  Gets the denominator part of the fraction.

  Returns:

  the denominator fraction part

• getProperNumerator

  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.

  Returns:

  the numerator fraction part of a proper fraction, always positive

• getProperWhole

  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.

  Returns:

  the whole fraction part of a proper fraction, that includes the sign

• intValue

  public int intValue()

  Gets the fraction as an int. This returns the whole number part of the fraction.

  Specified by:

  intValue in class Number

  Returns:

  the whole number fraction part

• longValue

  public long longValue()

  Gets the fraction as a long. This returns the whole number part of the fraction.

  Specified by:

  longValue in class Number

  Returns:

  the whole number fraction part

• floatValue

  public float floatValue()

  Gets the fraction as a float. This calculates the fraction as the numerator divided by denominator.

  Specified by:

  floatValue in class Number

  Returns:

  the fraction as a float

• doubleValue

  public double doubleValue()

  Gets the fraction as a double. This calculates the fraction as the numerator divided by denominator.

  Specified by:

  doubleValue in class Number

  Returns:

  the fraction as a double

• reduce

  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.

  Returns:

  a new reduced fraction instance, or this if no simplification possible

• invert

  public Fraction invert()

  Gets a fraction that is the inverse (1/fraction) of this one.

  The returned fraction is not reduced.

  Returns:

  a new fraction instance with the numerator and denominator inverted.

  Throws:

  ArithmeticException - if the fraction represents zero.

• negate

  public Fraction negate()

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

  The returned fraction is not reduced.

  Returns:

  a new fraction instance with the opposite signed numerator

• abs

  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.

  Returns:

  this if it is positive, or a new positive fraction instance with the opposite signed numerator

• pow

  public Fraction pow(int power)

  Gets a fraction that is raised to the passed in power.

  The returned fraction is in reduced form.

  Parameters:

  power - the power to raise the fraction to

  Returns:

  this 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 power

  Throws:

  ArithmeticException - if the resulting numerator or denominator exceeds Integer.MAX_VALUE

• add

  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.

  Parameters:

  fraction - the fraction to add, must not be null

  Returns:

  a Fraction instance with the resulting values

  Throws:

  IllegalArgumentException - if the fraction is null

  ArithmeticException - if the resulting numerator or denominator exceeds Integer.MAX_VALUE

• subtract

  public Fraction subtract(Fraction fraction)

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

  Parameters:

  fraction - the fraction to subtract, must not be null

  Returns:

  a Fraction instance with the resulting values

  Throws:

  IllegalArgumentException - if the fraction is null

  ArithmeticException - if the resulting numerator or denominator cannot be represented in an int.

• multiplyBy

  public Fraction multiplyBy(Fraction fraction)

  Multiplies the value of this fraction by another, returning the result in reduced form.

  Parameters:

  fraction - the fraction to multiply by, must not be null

  Returns:

  a Fraction instance with the resulting values

  Throws:

  IllegalArgumentException - if the fraction is null

  ArithmeticException - if the resulting numerator or denominator exceeds Integer.MAX_VALUE

• divideBy

  public Fraction divideBy(Fraction fraction)

  Divide the value of this fraction by another.

  Parameters:

  fraction - the fraction to divide by, must not be null

  Returns:

  a Fraction instance with the resulting values

  Throws:

  IllegalArgumentException - if the fraction is null

  ArithmeticException - if the fraction to divide by is zero

  ArithmeticException - if the resulting numerator or denominator exceeds Integer.MAX_VALUE

• equals

  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.

  Overrides:

  equals in class Object

  Parameters:

  obj - the reference object with which to compare

  Returns:

  true if this object is equal

• hashCode

  public int hashCode()

  Gets a hashCode for the fraction.

  Overrides:

  hashCode in class Object

  Returns:

  a hash code value for this object

• compareTo

  public int compareTo(Object object)

  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.

  Specified by:

  compareTo in interface Comparable

  Parameters:

  object - the object to compare to

  Returns:

  -1 if this is less, 0 if equal, +1 if greater

  Throws:

  ClassCastException - if the object is not a Fraction

  NullPointerException - if the object is null

• toString

  public String toString()

  Gets the fraction as a String.

  The format used is 'numerator/denominator' always.

  Overrides:

  toString in class Object

  Returns:

  a String form of the fraction

• toProperString

  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 ommitted. If the numerator is zero, only the whole number is returned.

  Returns:

  a String form of the fraction