maspack.util
Class NumberFormat

java.lang.Object
  maspack.util.NumberFormat

public class NumberFormat

extends java.lang.Object

Object for formatting numbers in the same way similiar to the C printf function.

A printf style format string is specified in the constructor, or can be respecified using the set method. Once instantiated, the format methods of this class may be used to convert numeric types (float, double, int, long) into Strings.

Examples:

  
   double theta1 = 45.0;
   double theta2 = 85.0;
   NumberFormat fmt = new NumberFormat ("%7.2f\n");
   
   System.out.println ("theta1=" + fmt.format(theta1) +
                       "theta2=" + fmt.format(theta2)); 
 

Author:

John E. Lloyd, Winter 2004

Constructor Summary

NumberFormat()
Creates a new instance of PrintfFormat with the default format string %g.

NumberFormat(java.lang.String fmtStr)
Creates a new instance of PrintfFormat from the supplied format string.

Method Summary

java.lang.String	format(double x) Formats a double into a string.
java.lang.StringBuffer	format(double x, java.lang.StringBuffer sbuf) Formats a double and appends it to the end of a StringBuffer.
java.lang.String	format(int x) Formats an int into a string.
java.lang.StringBuffer	format(int x, java.lang.StringBuffer sbuf) Formats an int and appends it to the end of a StringBuffer.
java.lang.String	format(long x) Formats a long into a string.
java.lang.StringBuffer	format(long x, java.lang.StringBuffer sbuf) Formats a long and appends it to the end of a StringBuffer.
int	getFieldWidth() Returns the field width associated with this format.
int	getPrecision() Returns the precision associated with this format.
java.lang.String	getPrefix() Gets the prefix associated with this format.
java.lang.String	getSuffix() Gets the suffix associated with this format.
void	set(java.lang.String fmtStr) Sets the format characteristics according to the supplied String.
void	setFieldWidth(int w) Sets the field width associated with this format.
void	setPrecision(int p) Sets the precision associated with this format.
void	setPrefix(java.lang.String pre) Sets the prefix associated with this format.
void	setSuffix(java.lang.String suf) Sets the suffix associated with this format.

Methods inherited from class java.lang.Object

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

Constructor Detail

NumberFormat

public NumberFormat()

Creates a new instance of PrintfFormat with the default format string %g.

NumberFormat

public NumberFormat(java.lang.String fmtStr)

Creates a new instance of PrintfFormat from the supplied format string. The structure of the format string is described in the documentation for set.

Parameters:

fmtStr - Format string

Throws:

java.lang.IllegalArgumentException - Malformed format string

See Also:

set(java.lang.String)

Method Detail

setFieldWidth

public void setFieldWidth(int w)

Sets the field width associated with this format. The numeric portion of the final formatted string is padded to ensure that it is at least this width.

Parameters:

w - field width

Throws:

java.lang.IllegalArgumentException - Negative field width

See Also:

getFieldWidth(), set(java.lang.String)

getFieldWidth

public int getFieldWidth()

Returns the field width associated with this format.

Returns:

field width

See Also:

setFieldWidth(int), set(java.lang.String)

setPrecision

public void setPrecision(int p)

Sets the precision associated with this format. For a floating point type, the precision generally gives the number of digits that appear after the decimal point. For more precise details, see the documentation for set. A negative value implies either that no precision is set, or a default value should be set.

Parameters:

p - precision

See Also:

getPrecision(), set(java.lang.String)

getPrecision

public int getPrecision()

Returns the precision associated with this format.

Returns:

precision

See Also:

setPrecision(int), set(java.lang.String)

setPrefix

public void setPrefix(java.lang.String pre)

Sets the prefix associated with this format. The prefix is the (possibly empty) string that precedes the numeric part.

Parameters:

pre - new prefix

See Also:

getPrefix()

getPrefix

public java.lang.String getPrefix()

Gets the prefix associated with this format.

Returns:

prefix

setSuffix

public void setSuffix(java.lang.String suf)

Sets the suffix associated with this format. The suffix is the (possibly empty) string that follows the numeric part.

Parameters:

suf - new suffix

See Also:

getSuffix()

getSuffix

public java.lang.String getSuffix()

Gets the suffix associated with this format.

Returns:

suffix

set

public void set(java.lang.String fmtStr)
         throws java.lang.IllegalArgumentException

Sets the format characteristics according to the supplied String.

The format string has a format similar to the one used by the C printf function, except that only one conversion may be specified.

The format string consists of an optional prefix of regular characters, followed by a conversion sequence, followed by an optional suffix of regular characters.

The conversion sequence is introduced by a '%' character, and is followed by any number of optional flag characters, an optional unsigned decimal integer specifying a field width, another optional unsigned decimal integer (preceded by a '.' character) specifying a precision, and finally a conversion character. To incorporate a '%' character into either the prefix or suffix, one should specify the sequence "%%". The allowed flag characters are:

#

The value is converted into an "alternate" form. For 'o' conversions, the output is always prefixed with a '0'. For 'x' and 'X' conversions, the output is prefixed with "0x" or "0X", respectively. For 'a', 'A', 'e', 'E', and 'f' conversions, the result will always contain a decimal point. There is no effect for other conversions.

0

Use '0' to pad the field on the left, instead of blanks. If the conversion is 'd', 'i', 'o', 'u', 'x', or 'X', and a precision is given, then this flag is ignored.

-

The output is aligned with the left of the field boundary, and padded on the right with blanks. This flag overrides the '0' flag.

' '

Leave a blank before a positive number produced by a signed conversion.

+

A '+' sign is placed before non-negative numbers produced by a signed conversion. This flag overrides the ' ' flag.

The conversion character is one of:

d,i

The integer argument is output as a signed decimal number. If a precision is given, it describes the minimum number of digits that must appear (default 1). If the precision exceeds the number of digits that would normally appear, the output is padded on the left with zeros. When 0 is printed with precision 0, the result is empty.

o,u,x,X

The integer argument is output as an unsigned number in either octal ('o'), decimal ('u'), or hexadecimal ('x' or 'X'). The digits "abcdef" are used for 'x', and "ABCDEF" are used for 'X'. If a precision is given, it describes the minimum number of digits that must appear (default 1). If the precision exceeds the number of digits that would normally appear, the output is padded on the left with zeros. When 0 is printed with precision 0, the result is empty.

e,E

The floating point argument is output in the exponential form [-]d.ddde+dd, with the number of digits after the decimal point given by the precision. The default precision value is 6. No decimal point is output if the precision is 0. Conversion 'E' causes 'E' to be used as an exponent instead of 'e'. The exponent is always at least two characters.

f

The floating point argument is output in the form [-]ddd.ddd, with the number of digits after the decimal point given by the precision. The default precision value is 6. No decimal point is output if the precision is 0. If a decimal point appears, at least one digit appears before it.

g

The floating point argument is output using the Java Double.toString method. This produces a decimal representation that is accurate enough to reproduce the number exactly if it is read back into a Java application using Double.parseDouble. Note that this is different from the usual C printf interpretation of %g.

a,A

The floating point argument is output in the hexadecimal floating point form [-]0xh.hhhp+dd. The exponent is a decimal number and describes a power of 2. The 'A' style uses the prefix "0X", the hex digits "ABCDEF", and the exponent character 'P'. The number of digits after the decimal point is given by the precision. The default precision is enough for an exact representation of the value.

Parameters:

fmtStr - Format string

Throws:

java.lang.IllegalArgumentException - Malformed format string

format

public java.lang.String format(double x)

Formats a double into a string.

Parameters:

x - value to be formatted

Returns:

formatted string

format

public java.lang.StringBuffer format(double x,
                                     java.lang.StringBuffer sbuf)

Formats a double and appends it to the end of a StringBuffer.

Parameters:

x - value to be formatted

sbuf - buffer to place the result in

Returns:

pointer to the result buffer

format

public java.lang.String format(int x)

Formats an int into a string.

Parameters:

x - value to be formatted

Returns:

formatted string

format

public java.lang.StringBuffer format(int x,
                                     java.lang.StringBuffer sbuf)

Formats an int and appends it to the end of a StringBuffer.

Parameters:

x - value to be formatted

sbuf - buffer to place the result in

Returns:

pointer to the result buffer

format

public java.lang.String format(long x)

Formats a long into a string.

Parameters:

x - value to be formatted

Returns:

formatted string

format

public java.lang.StringBuffer format(long x,
                                     java.lang.StringBuffer sbuf)

Formats a long and appends it to the end of a StringBuffer.

Parameters:

x - value to be formatted

sbuf - buffer to place the result in

Returns:

pointer to the result buffer