Class NumberFunction

java.lang.Object
org.jaxen.function.NumberFunction
All Implemented Interfaces:
Function
public class NumberFunction extends Object implements Function

4.4 number number(object)

The number function converts its argument to a number as follows:

  • a string that consists of optional whitespace followed by an optional minus sign followed by a Number followed by whitespace is converted to the IEEE 754 number that is nearest (according to the IEEE 754 round-to-nearest rule) to the mathematical value represented by the string; any other string is converted to NaN

  • boolean true is converted to 1; boolean false is converted to 0

  • a node-set is first converted to a string as if by a call to the string function and then converted in the same way as a string argument

  • an object of a type other than the four basic types is converted to a number in a way that is dependent on that type

If the argument is omitted, it defaults to a node-set with the context node as its only member.

NOTE: The number function should not be used for conversion of numeric data occurring in an element in an XML document unless the element is of a type that represents numeric data in a language-neutral format (which would typically be transformed into a language-specific format for presentation to a user). In addition, the number function cannot be used unless the language-neutral format used by the element is consistent with the XPath syntax for a Number.
See Also:

  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    private static final Double
    NaN
     

  • Constructor Summary

    Constructors
    Constructor
    Description
    NumberFunction()
    Create a new NumberFunction object.

  • Method Summary

    Modifier and Type
    Method
    Description
    Object
    call(Context context, List args)
    Returns the number value of args.get(0), or the number value of the context node if args is empty.
    static Double
    evaluate(Object obj, Navigator nav)
    Returns the number value of obj.
    static boolean
    isNaN(double val)
    Determines whether the argument is not a number (NaN) as defined by IEEE 754.
    static boolean
    isNaN(Double val)
    Determines whether the argument is not a number (NaN) as defined by IEEE 754.

    Methods inherited from class Object

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

  • Field Details

    • NaN

      private static final Double NaN

  • Constructor Details

    • NumberFunction

      public NumberFunction()
      Create a new NumberFunction object.

  • Method Details

    • call

      public Object call(Context context, List args) throws FunctionCallException
      Returns the number value of args.get(0), or the number value of the context node if args is empty.
      Specified by:
      call in interface Function
      Parameters:
      context - the context at the point in the expression when the function is called
      args - a list containing the single item to be converted to a Double
      Returns:
      a Double
      Throws:
      FunctionCallException - if args has more than one item

    • evaluate

      public static Double evaluate(Object obj, Navigator nav)
      Returns the number value of obj.
      Parameters:
      obj - the object to be converted to a number
      nav - the Navigator used to calculate the string-value of node-sets
      Returns:
      a Double

    • isNaN

      public static boolean isNaN(double val)
      Determines whether the argument is not a number (NaN) as defined by IEEE 754.
      Parameters:
      val - the double to test
      Returns:
      true if the value is NaN, false otherwise

    • isNaN

      public static boolean isNaN(Double val)
      Determines whether the argument is not a number (NaN) as defined by IEEE 754.
      Parameters:
      val - the Double to test
      Returns:
      true if the value is NaN, false otherwise