corejava

Class Format

java.lang.Object

corejava.Format

public class Format
extends Object

A class for formatting numbers that follows printf conventions. Also implements C-like atoi and atof functions

Version:

1.22 2002-11-16

Author:

Cay Horstmann 1998-09-14: Fixed a number of bugs. 1.Formatting the most extreme negative number (-9223372036854775808L) printed with 2 leading minus signs. 2.Printing 0 with a %e or %g format did not work. 3.Printing numbers that were closer to 1 than the number of requested decimal places rounded down rather than up, e.g. formatting 1.999 with %.2f printed 1.00. (This one is pretty serious, of course.) 4.Printing with precision 0 (e.g %10.0f) didn't work. 5.Printing a string with a precision that exceeded the string length (e.g. print "Hello" with %20.10s) caused a StringIndexOutOfBounds error. 1998-10-21: Changed method names from print to printf 2000-06-09: Moved to package com.horstmann; no longer part of Core Java 2000-06-09: Fixed a number of bugs. 1.Printing 100.0 with %e printed 10.0e1, not 1.0e2 2.Printing Inf and NaN didn't work. 2000-06-09: Coding guideline cleanup 2002-11-16: Move to package com.horstmann.format; licensed under LGPL

Constructor Summary

Constructors

Constructor and Description
Format(String s) Formats the number following printf conventions.

Method Summary

Methods

Modifier and Type	Method and Description
static double	atof(String s) Converts a string of digits to a double
static int	atoi(String s) Converts a string of digits (decimal, octal or hex) to an integer
static long	atol(String s) Converts a string of digits (decimal, octal or hex) to a long integer
String	format(char c) Formats a character into a string (like sprintf in C)
String	format(double x) Formats a double into a string (like sprintf in C)
String	format(int x) Formats an integer into a string (like sprintf in C)
String	format(long x) Formats a long integer into a string (like sprintf in C)
String	format(String s) Formats a string into a larger string (like sprintf in C)
static void	main(String[] a) a test stub for the format class
static void	printf(String fmt, char x) prints a formatted number following printf conventions
static void	printf(String fmt, double x) prints a formatted number following printf conventions
static void	printf(String fmt, int x) prints a formatted number following printf conventions
static void	printf(String fmt, long x) prints a formatted number following printf conventions
static void	printf(String fmt, String x) prints a formatted number following printf conventions

Methods inherited from class java.lang.Object

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

Constructor Detail

Format

public Format(String s)

Formats the number following printf conventions. Main limitation: Can only handle one format parameter at a time Use multiple Format objects to format more than one number

Parameters:

s - the format string following printf conventions The string has a prefix, a format code and a suffix. The prefix and suffix become part of the formatted output. The format code directs the formatting of the (single) parameter to be formatted. The code has the following structure

• a % (required)
• a modifier (optional)

  +

  forces display of + for positive numbers

  0

  show leading zeroes

  -

  align left in the field

  space

  prepend a space in front of positive numbers

  #

  use "alternate" format. Add 0 or 0x for octal or hexadecimal numbers. Don't suppress trailing zeroes in general floating point format.

• an integer denoting field width (optional)
• a period followed by an integer denoting precision (optional)
• a format descriptor (required)

  f

  floating point number in fixed format

  e, E

  floating point number in exponential notation (scientific format). The E format results in an uppercase E for the exponent (1.14130E+003), the e format in a lowercase e.

  g, G

  floating point number in general format (fixed format for small numbers, exponential format for large numbers). Trailing zeroes are suppressed. The G format results in an uppercase E for the exponent (if any), the g format in a lowercase e.

  d, i

  integer in decimal

  x

  integer in hexadecimal

  o

  integer in octal

  s

  string

  c

  character

Throws:

IllegalArgumentException - if bad format

Method Detail

printf

public static void printf(String fmt,
          double x)

prints a formatted number following printf conventions

Parameters:

fmt - the format string

x - the double to print

printf

public static void printf(String fmt,
          int x)

prints a formatted number following printf conventions

Parameters:

fmt - the format string

x - the int to print

printf

public static void printf(String fmt,
          long x)

prints a formatted number following printf conventions

Parameters:

fmt - the format string

x - the long to print

printf

public static void printf(String fmt,
          char x)

prints a formatted number following printf conventions

Parameters:

fmt - the format string

x - the character to print

printf

public static void printf(String fmt,
          String x)

prints a formatted number following printf conventions

Parameters:

fmt - the format string

x - a string to print

atoi

public static int atoi(String s)

Converts a string of digits (decimal, octal or hex) to an integer

Parameters:

s - a string

Returns:

the numeric value of the prefix of s representing a base 10 integer

atol

public static long atol(String s)

Converts a string of digits (decimal, octal or hex) to a long integer

Parameters:

s - a string

Returns:

the numeric value of the prefix of s representing a base 10 integer

atof

public static double atof(String s)

Converts a string of digits to a double

Parameters:

s - a string

format

public String format(double x)

Formats a double into a string (like sprintf in C)

Parameters:

x - the number to format

Returns:

the formatted string

Throws:

IllegalArgumentException - if bad argument

format

public String format(int x)

Formats an integer into a string (like sprintf in C)

Parameters:

x - the number to format

Returns:

the formatted string

format

public String format(long x)

Formats a long integer into a string (like sprintf in C)

Parameters:

x - the number to format

Returns:

the formatted string

format

public String format(char c)

Formats a character into a string (like sprintf in C)

Parameters:

x - the value to format

Returns:

the formatted string

format

public String format(String s)

Formats a string into a larger string (like sprintf in C)

Parameters:

x - the value to format

Returns:

the formatted string

main

public static void main(String[] a)

a test stub for the format class