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

  • Method Summary

    Modifier and Type
    Method
    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 Details

    • 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 Details

    • 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