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*/
/** * An interpreter for printf-style format strings. This class provides support * for layout justification and alignment, common formats for numeric, string, * and date/time data, and locale-specific output. Common Java types such as * {@code byte}, {@link java.math.BigDecimal BigDecimal}, and {@link Calendar} * are supported. Limited formatting customization for arbitrary user types is * provided through the {@link Formattable} interface. * * <p> Formatters are not necessarily safe for multithreaded access. Thread * safety is optional and is the responsibility of users of methods in this * class. * * <p> Formatted printing for the Java language is heavily inspired by C's * {@code printf}. Although the format strings are similar to C, some * customizations have been made to accommodate the Java language and exploit * some of its features. Also, Java formatting is more strict than C's; for * example, if a conversion is incompatible with a flag, an exception will be * thrown. In C inapplicable flags are silently ignored. The format strings * are thus intended to be recognizable to C programmers but not necessarily * completely compatible with those in C. * * <p> Examples of expected usage: * * <blockquote><pre> * StringBuilder sb = new StringBuilder(); * // Send all output to the Appendable object sb * Formatter formatter = new Formatter(sb, Locale.US); * * // Explicit argument indices may be used to re-order output. * formatter.format("%4$2s %3$2s %2$2s %1$2s", "a", "b", "c", "d") * // -> " d c b a" * * // Optional locale as the first argument can be used to get * // locale-specific formatting of numbers. The precision and width can be * // given to round and align the value. * formatter.format(Locale.FRANCE, "e = %+10.4f", Math.E); * // -> "e = +2,7183" * * // The '(' numeric flag may be used to format negative numbers with * // parentheses rather than a minus sign. Group separators are * // automatically inserted. * formatter.format("Amount gained or lost since last statement: $ %(,.2f", * balanceDelta); * // -> "Amount gained or lost since last statement: $ (6,217.58)" * </pre></blockquote> * * <p> Convenience methods for common formatting requests exist as illustrated * by the following invocations: * * <blockquote><pre> * // Writes a formatted string to System.out. * System.out.format("Local time: %tT", Calendar.getInstance()); * // -> "Local time: 13:34:18" * * // Writes formatted output to System.err. * System.err.printf("Unable to open file '%1$s': %2$s", * fileName, exception.getMessage()); * // -> "Unable to open file 'food': No such file or directory" * </pre></blockquote> * * <p> Like C's {@code sprintf(3)}, Strings may be formatted using the static * method {@link String#format(String,Object...) String.format}: * * <blockquote><pre> * // Format a string containing a date. * import java.util.Calendar; * import java.util.GregorianCalendar; * import static java.util.Calendar.*; * * Calendar c = new GregorianCalendar(1995, MAY, 23); * String s = String.format("Duke's Birthday: %1$tb %1$te, %1$tY", c); * // -> s == "Duke's Birthday: May 23, 1995" * </pre></blockquote> * * <h2><a id="org">Organization</a></h2> * * <p> This specification is divided into two sections. The first section, <a * href="#summary">Summary</a>, covers the basic formatting concepts. This * section is intended for users who want to get started quickly and are * familiar with formatted printing in other programming languages. The second * section, <a href="#detail">Details</a>, covers the specific implementation * details. It is intended for users who want more precise specification of * formatting behavior. * * <h2><a id="summary">Summary</a></h2> * * <p> This section is intended to provide a brief overview of formatting * concepts. For precise behavioral details, refer to the <a * href="#detail">Details</a> section. * * <h3><a id="syntax">Format String Syntax</a></h3> * * <p> Every method which produces formatted output requires a <i>format * string</i> and an <i>argument list</i>. The format string is a {@link * String} which may contain fixed text and one or more embedded <i>format * specifiers</i>. Consider the following example: * * <blockquote><pre> * Calendar c = ...; * String s = String.format("Duke's Birthday: %1$tm %1$te,%1$tY", c); * </pre></blockquote> * * This format string is the first argument to the {@code format} method. It * contains three format specifiers "{@code %1$tm}", "{@code %1$te}", and * "{@code %1$tY}" which indicate how the arguments should be processed and * where they should be inserted in the text. The remaining portions of the * format string are fixed text including {@code "Dukes Birthday: "} and any * other spaces or punctuation. * * The argument list consists of all arguments passed to the method after the * format string. In the above example, the argument list is of size one and * consists of the {@link java.util.Calendar Calendar} object {@code c}. * * <ul> * * <li> The format specifiers for general, character, and numeric types have * the following syntax: * * <blockquote><pre> * %[argument_index$][flags][width][.precision]conversion * </pre></blockquote> * * <p> The optional <i>argument_index</i> is a decimal integer indicating the * position of the argument in the argument list. The first argument is * referenced by "{@code 1$}", the second by "{@code 2$}", etc. * * <p> The optional <i>flags</i> is a set of characters that modify the output * format. The set of valid flags depends on the conversion. * * <p> The optional <i>width</i> is a positive decimal integer indicating * the minimum number of characters to be written to the output. * * <p> The optional <i>precision</i> is a non-negative decimal integer usually * used to restrict the number of characters. The specific behavior depends on * the conversion. * * <p> The required <i>conversion</i> is a character indicating how the * argument should be formatted. The set of valid conversions for a given * argument depends on the argument's data type. * * <li> The format specifiers for types which are used to represents dates and * times have the following syntax: * * <blockquote><pre> * %[argument_index$][flags][width]conversion * </pre></blockquote> * * <p> The optional <i>argument_index</i>, <i>flags</i> and <i>width</i> are * defined as above. * * <p> The required <i>conversion</i> is a two character sequence. The first * character is {@code 't'} or {@code 'T'}. The second character indicates * the format to be used. These characters are similar to but not completely * identical to those defined by GNU {@code date} and POSIX * {@code strftime(3c)}. * * <li> The format specifiers which do not correspond to arguments have the * following syntax: * * <blockquote><pre> * %[flags][width]conversion * </pre></blockquote> * * <p> The optional <i>flags</i> and <i>width</i> is defined as above. * * <p> The required <i>conversion</i> is a character indicating content to be * inserted in the output. * * </ul> * * <h3> Conversions </h3> * * <p> Conversions are divided into the following categories: * * <ol> * * <li> <b>General</b> - may be applied to any argument * type * * <li> <b>Character</b> - may be applied to basic types which represent * Unicode characters: {@code char}, {@link Character}, {@code byte}, {@link * Byte}, {@code short}, and {@link Short}. This conversion may also be * applied to the types {@code int} and {@link Integer} when {@link * Character#isValidCodePoint} returns {@code true} * * <li> <b>Numeric</b> * * <ol> * * <li> <b>Integral</b> - may be applied to Java integral types: {@code byte}, * {@link Byte}, {@code short}, {@link Short}, {@code int} and {@link * Integer}, {@code long}, {@link Long}, and {@link java.math.BigInteger * BigInteger} (but not {@code char} or {@link Character}) * * <li><b>Floating Point</b> - may be applied to Java floating-point types: * {@code float}, {@link Float}, {@code double}, {@link Double}, and {@link * java.math.BigDecimal BigDecimal} * * </ol> * * <li> <b>Date/Time</b> - may be applied to Java types which are capable of * encoding a date or time: {@code long}, {@link Long}, {@link Calendar}, * {@link Date} and {@link TemporalAccessor TemporalAccessor} * * <li> <b>Percent</b> - produces a literal {@code '%'} * (<code>'\u0025'</code>) * * <li> <b>Line Separator</b> - produces the platform-specific line separator * * </ol> * * <p> For category <i>General</i>, <i>Character</i>, <i>Numeric</i>, * <i>Integral</i> and <i>Date/Time</i> conversion, unless otherwise specified, * if the argument <i>arg</i> is {@code null}, then the result is "{@code null}". * * <p> The following table summarizes the supported conversions. Conversions * denoted by an upper-case character (i.e. {@code 'B'}, {@code 'H'}, * {@code 'S'}, {@code 'C'}, {@code 'X'}, {@code 'E'}, {@code 'G'}, * {@code 'A'}, and {@code 'T'}) are the same as those for the corresponding * lower-case conversion characters except that the result is converted to * upper case according to the rules of the prevailing {@link java.util.Locale * Locale}. If there is no explicit locale specified, either at the * construction of the instance or as a parameter to its method * invocation, then the {@link java.util.Locale.Category#FORMAT default locale} * is used. * * * <table class="striped"> * <caption style="display:none">genConv</caption> * <thead> * <tr><th scope="col" style="vertical-align:bottom"> Conversion * <th scope="col" style="vertical-align:bottom"> Argument Category * <th scope="col" style="vertical-align:bottom"> Description * </thead> * <tbody> * <tr><th scope="row" style="vertical-align:top"> {@code 'b'}, {@code 'B'} * <td style="vertical-align:top"> general * <td> If the argument <i>arg</i> is {@code null}, then the result is * "{@code false}". If <i>arg</i> is a {@code boolean} or {@link * Boolean}, then the result is the string returned by {@link * String#valueOf(boolean) String.valueOf(arg)}. Otherwise, the result is * "true". * * <tr><th scope="row" style="vertical-align:top"> {@code 'h'}, {@code 'H'} * <td style="vertical-align:top"> general * <td> The result is obtained by invoking * {@code Integer.toHexString(arg.hashCode())}. * * <tr><th scope="row" style="vertical-align:top"> {@code 's'}, {@code 'S'} * <td style="vertical-align:top"> general * <td> If <i>arg</i> implements {@link Formattable}, then * {@link Formattable#formatTo arg.formatTo} is invoked. Otherwise, the * result is obtained by invoking {@code arg.toString()}. * * <tr><th scope="row" style="vertical-align:top">{@code 'c'}, {@code 'C'} * <td style="vertical-align:top"> character * <td> The result is a Unicode character * * <tr><th scope="row" style="vertical-align:top">{@code 'd'} * <td style="vertical-align:top"> integral * <td> The result is formatted as a decimal integer * * <tr><th scope="row" style="vertical-align:top">{@code 'o'} * <td style="vertical-align:top"> integral * <td> The result is formatted as an octal integer * * <tr><th scope="row" style="vertical-align:top">{@code 'x'}, {@code 'X'} * <td style="vertical-align:top"> integral * <td> The result is formatted as a hexadecimal integer * * <tr><th scope="row" style="vertical-align:top">{@code 'e'}, {@code 'E'} * <td style="vertical-align:top"> floating point * <td> The result is formatted as a decimal number in computerized * scientific notation * * <tr><th scope="row" style="vertical-align:top">{@code 'f'} * <td style="vertical-align:top"> floating point * <td> The result is formatted as a decimal number * * <tr><th scope="row" style="vertical-align:top">{@code 'g'}, {@code 'G'} * <td style="vertical-align:top"> floating point * <td> The result is formatted using computerized scientific notation or * decimal format, depending on the precision and the value after rounding. * * <tr><th scope="row" style="vertical-align:top">{@code 'a'}, {@code 'A'} * <td style="vertical-align:top"> floating point * <td> The result is formatted as a hexadecimal floating-point number with * a significand and an exponent. This conversion is <b>not</b> supported * for the {@code BigDecimal} type despite the latter's being in the * <i>floating point</i> argument category. * * <tr><th scope="row" style="vertical-align:top">{@code 't'}, {@code 'T'} * <td style="vertical-align:top"> date/time * <td> Prefix for date and time conversion characters. See <a * href="#dt">Date/Time Conversions</a>. * * <tr><th scope="row" style="vertical-align:top">{@code '%'} * <td style="vertical-align:top"> percent * <td> The result is a literal {@code '%'} (<code>'\u0025'</code>) * * <tr><th scope="row" style="vertical-align:top">{@code 'n'} * <td style="vertical-align:top"> line separator * <td> The result is the platform-specific line separator * * </tbody> * </table> * * <p> Any characters not explicitly defined as conversions are illegal and are * reserved for future extensions. * * <h3><a id="dt">Date/Time Conversions</a></h3> * * <p> The following date and time conversion suffix characters are defined for * the {@code 't'} and {@code 'T'} conversions. The types are similar to but * not completely identical to those defined by GNU {@code date} and POSIX * {@code strftime(3c)}. Additional conversion types are provided to access * Java-specific functionality (e.g. {@code 'L'} for milliseconds within the * second). * * <p> The following conversion characters are used for formatting times: * * <table class="striped"> * <caption style="display:none">time</caption> * <thead> * <tr><th scope="col" style="vertical-align:bottom"> Conversion * <th scope="col" style="vertical-align:bottom"> Description * </thead> * <tbody> * <tr><th scope="row" style="vertical-align:top"> {@code 'H'} * <td> Hour of the day for the 24-hour clock, formatted as two digits with * a leading zero as necessary i.e. {@code 00 - 23}. * * <tr><th scope="row" style="vertical-align:top">{@code 'I'} * <td> Hour for the 12-hour clock, formatted as two digits with a leading * zero as necessary, i.e. {@code 01 - 12}. * * <tr><th scope="row" style="vertical-align:top">{@code 'k'} * <td> Hour of the day for the 24-hour clock, i.e. {@code 0 - 23}. * * <tr><th scope="row" style="vertical-align:top">{@code 'l'} * <td> Hour for the 12-hour clock, i.e. {@code 1 - 12}. * * <tr><th scope="row" style="vertical-align:top">{@code 'M'} * <td> Minute within the hour formatted as two digits with a leading zero * as necessary, i.e. {@code 00 - 59}. * * <tr><th scope="row" style="vertical-align:top">{@code 'S'} * <td> Seconds within the minute, formatted as two digits with a leading * zero as necessary, i.e. {@code 00 - 60} ("{@code 60}" is a special * value required to support leap seconds). * * <tr><th scope="row" style="vertical-align:top">{@code 'L'} * <td> Millisecond within the second formatted as three digits with * leading zeros as necessary, i.e. {@code 000 - 999}. * * <tr><th scope="row" style="vertical-align:top">{@code 'N'} * <td> Nanosecond within the second, formatted as nine digits with leading * zeros as necessary, i.e. {@code 000000000 - 999999999}. * * <tr><th scope="row" style="vertical-align:top">{@code 'p'} * <td> Locale-specific {@linkplain * java.text.DateFormatSymbols#getAmPmStrings morning or afternoon} marker * in lower case, e.g."{@code am}" or "{@code pm}". Use of the conversion * prefix {@code 'T'} forces this output to upper case. * * <tr><th scope="row" style="vertical-align:top">{@code 'z'} * <td> <a href="http://www.ietf.org/rfc/rfc0822.txt">RFC 822</a> * style numeric time zone offset from GMT, e.g. {@code -0800}. This * value will be adjusted as necessary for Daylight Saving Time. For * {@code long}, {@link Long}, and {@link Date} the time zone used is * the {@linkplain TimeZone#getDefault() default time zone} for this * instance of the Java virtual machine. * * <tr><th scope="row" style="vertical-align:top">{@code 'Z'} * <td> A string representing the abbreviation for the time zone. This * value will be adjusted as necessary for Daylight Saving Time. For * {@code long}, {@link Long}, and {@link Date} the time zone used is * the {@linkplain TimeZone#getDefault() default time zone} for this * instance of the Java virtual machine. The Formatter's locale will * supersede the locale of the argument (if any). * * <tr><th scope="row" style="vertical-align:top">{@code 's'} * <td> Seconds since the beginning of the epoch starting at 1 January 1970 * {@code 00:00:00} UTC, i.e. {@code Long.MIN_VALUE/1000} to * {@code Long.MAX_VALUE/1000}. * * <tr><th scope="row" style="vertical-align:top">{@code 'Q'} * <td> Milliseconds since the beginning of the epoch starting at 1 January * 1970 {@code 00:00:00} UTC, i.e. {@code Long.MIN_VALUE} to * {@code Long.MAX_VALUE}. * * </tbody> * </table> * * <p> The following conversion characters are used for formatting dates: * * <table class="striped"> * <caption style="display:none">date</caption> * <thead> * <tr><th scope="col" style="vertical-align:bottom"> Conversion * <th scope="col" style="vertical-align:bottom"> Description * </thead> * <tbody> * * <tr><th scope="row" style="vertical-align:top">{@code 'B'} * <td> Locale-specific {@linkplain java.text.DateFormatSymbols#getMonths * full month name}, e.g. {@code "January"}, {@code "February"}. * * <tr><th scope="row" style="vertical-align:top">{@code 'b'} * <td> Locale-specific {@linkplain * java.text.DateFormatSymbols#getShortMonths abbreviated month name}, * e.g. {@code "Jan"}, {@code "Feb"}. * * <tr><th scope="row" style="vertical-align:top">{@code 'h'} * <td> Same as {@code 'b'}. * * <tr><th scope="row" style="vertical-align:top">{@code 'A'} * <td> Locale-specific full name of the {@linkplain * java.text.DateFormatSymbols#getWeekdays day of the week}, * e.g. {@code "Sunday"}, {@code "Monday"} * * <tr><th scope="row" style="vertical-align:top">{@code 'a'} * <td> Locale-specific short name of the {@linkplain * java.text.DateFormatSymbols#getShortWeekdays day of the week}, * e.g. {@code "Sun"}, {@code "Mon"} * * <tr><th scope="row" style="vertical-align:top">{@code 'C'} * <td> Four-digit year divided by {@code 100}, formatted as two digits * with leading zero as necessary, i.e. {@code 00 - 99} * * <tr><th scope="row" style="vertical-align:top">{@code 'Y'} * <td> Year, formatted as at least four digits with leading zeros as * necessary, e.g. {@code 0092} equals {@code 92} CE for the Gregorian * calendar. * * <tr><th scope="row" style="vertical-align:top">{@code 'y'} * <td> Last two digits of the year, formatted with leading zeros as * necessary, i.e. {@code 00 - 99}. * * <tr><th scope="row" style="vertical-align:top">{@code 'j'} * <td> Day of year, formatted as three digits with leading zeros as * necessary, e.g. {@code 001 - 366} for the Gregorian calendar. * * <tr><th scope="row" style="vertical-align:top">{@code 'm'} * <td> Month, formatted as two digits with leading zeros as necessary, * i.e. {@code 01 - 13}. * * <tr><th scope="row" style="vertical-align:top">{@code 'd'} * <td> Day of month, formatted as two digits with leading zeros as * necessary, i.e. {@code 01 - 31} * * <tr><th scope="row" style="vertical-align:top">{@code 'e'} * <td> Day of month, formatted as two digits, i.e. {@code 1 - 31}. * * </tbody> * </table> * * <p> The following conversion characters are used for formatting common * date/time compositions. * * <table class="striped"> * <caption style="display:none">composites</caption> * <thead> * <tr><th scope="col" style="vertical-align:bottom"> Conversion * <th scope="col" style="vertical-align:bottom"> Description * </thead> * <tbody> * * <tr><th scope="row" style="vertical-align:top">{@code 'R'} * <td> Time formatted for the 24-hour clock as {@code "%tH:%tM"} * * <tr><th scope="row" style="vertical-align:top">{@code 'T'} * <td> Time formatted for the 24-hour clock as {@code "%tH:%tM:%tS"}. * * <tr><th scope="row" style="vertical-align:top">{@code 'r'} * <td> Time formatted for the 12-hour clock as {@code "%tI:%tM:%tS %Tp"}. * The location of the morning or afternoon marker ({@code '%Tp'}) may be * locale-dependent. * * <tr><th scope="row" style="vertical-align:top">{@code 'D'} * <td> Date formatted as {@code "%tm/%td/%ty"}. * * <tr><th scope="row" style="vertical-align:top">{@code 'F'} * <td> <a href="http://www.w3.org/TR/NOTE-datetime">ISO 8601</a> * complete date formatted as {@code "%tY-%tm-%td"}. * * <tr><th scope="row" style="vertical-align:top">{@code 'c'} * <td> Date and time formatted as {@code "%ta %tb %td %tT %tZ %tY"}, * e.g. {@code "Sun Jul 20 16:17:00 EDT 1969"}. * * </tbody> * </table> * * <p> Any characters not explicitly defined as date/time conversion suffixes * are illegal and are reserved for future extensions. * * <h3> Flags </h3> * * <p> The following table summarizes the supported flags. <i>y</i> means the * flag is supported for the indicated argument types. * * <table class="striped"> * <caption style="display:none">genConv</caption> * <thead> * <tr><th scope="col" style="vertical-align:bottom"> Flag <th scope="col" style="vertical-align:bottom"> General * <th scope="col" style="vertical-align:bottom"> Character <th scope="col" style="vertical-align:bottom"> Integral * <th scope="col" style="vertical-align:bottom"> Floating Point * <th scope="col" style="vertical-align:bottom"> Date/Time * <th scope="col" style="vertical-align:bottom"> Description * </thead> * <tbody> * <tr><th scope="row"> '-' <td style="text-align:center; vertical-align:top"> y * <td style="text-align:center; vertical-align:top"> y * <td style="text-align:center; vertical-align:top"> y * <td style="text-align:center; vertical-align:top"> y * <td style="text-align:center; vertical-align:top"> y * <td> The result will be left-justified. * * <tr><th scope="row"> '#' <td style="text-align:center; vertical-align:top"> y<sup>1</sup> * <td style="text-align:center; vertical-align:top"> - * <td style="text-align:center; vertical-align:top"> y<sup>3</sup> * <td style="text-align:center; vertical-align:top"> y * <td style="text-align:center; vertical-align:top"> - * <td> The result should use a conversion-dependent alternate form * * <tr><th scope="row"> '+' <td style="text-align:center; vertical-align:top"> - * <td style="text-align:center; vertical-align:top"> - * <td style="text-align:center; vertical-align:top"> y<sup>4</sup> * <td style="text-align:center; vertical-align:top"> y * <td style="text-align:center; vertical-align:top"> - * <td> The result will always include a sign * * <tr><th scope="row"> ' ' <td style="text-align:center; vertical-align:top"> - * <td style="text-align:center; vertical-align:top"> - * <td style="text-align:center; vertical-align:top"> y<sup>4</sup> * <td style="text-align:center; vertical-align:top"> y * <td style="text-align:center; vertical-align:top"> - * <td> The result will include a leading space for positive values * * <tr><th scope="row"> '0' <td style="text-align:center; vertical-align:top"> - * <td style="text-align:center; vertical-align:top"> - * <td style="text-align:center; vertical-align:top"> y * <td style="text-align:center; vertical-align:top"> y * <td style="text-align:center; vertical-align:top"> - * <td> The result will be zero-padded * * <tr><th scope="row"> ',' <td style="text-align:center; vertical-align:top"> - * <td style="text-align:center; vertical-align:top"> - * <td style="text-align:center; vertical-align:top"> y<sup>2</sup> * <td style="text-align:center; vertical-align:top"> y<sup>5</sup> * <td style="text-align:center; vertical-align:top"> - * <td> The result will include locale-specific {@linkplain * java.text.DecimalFormatSymbols#getGroupingSeparator grouping separators} * * <tr><th scope="row"> '(' <td style="text-align:center; vertical-align:top"> - * <td style="text-align:center; vertical-align:top"> - * <td style="text-align:center; vertical-align:top"> y<sup>4</sup> * <td style="text-align:center; vertical-align:top"> y<sup>5</sup> * <td style="text-align:center"> - * <td> The result will enclose negative numbers in parentheses * * </tbody> * </table> * * <p> <sup>1</sup> Depends on the definition of {@link Formattable}. * * <p> <sup>2</sup> For {@code 'd'} conversion only. * * <p> <sup>3</sup> For {@code 'o'}, {@code 'x'}, and {@code 'X'} * conversions only. * * <p> <sup>4</sup> For {@code 'd'}, {@code 'o'}, {@code 'x'}, and * {@code 'X'} conversions applied to {@link java.math.BigInteger BigInteger} * or {@code 'd'} applied to {@code byte}, {@link Byte}, {@code short}, {@link * Short}, {@code int} and {@link Integer}, {@code long}, and {@link Long}. * * <p> <sup>5</sup> For {@code 'e'}, {@code 'E'}, {@code 'f'}, * {@code 'g'}, and {@code 'G'} conversions only. * * <p> Any characters not explicitly defined as flags are illegal and are * reserved for future extensions. * * <h3> Width </h3> * * <p> The width is the minimum number of characters to be written to the * output. For the line separator conversion, width is not applicable; if it * is provided, an exception will be thrown. * * <h3> Precision </h3> * * <p> For general argument types, the precision is the maximum number of * characters to be written to the output. * * <p> For the floating-point conversions {@code 'a'}, {@code 'A'}, {@code 'e'}, * {@code 'E'}, and {@code 'f'} the precision is the number of digits after the * radix point. If the conversion is {@code 'g'} or {@code 'G'}, then the * precision is the total number of digits in the resulting magnitude after * rounding. * * <p> For character, integral, and date/time argument types and the percent * and line separator conversions, the precision is not applicable; if a * precision is provided, an exception will be thrown. * * <h3> Argument Index </h3> * * <p> The argument index is a decimal integer indicating the position of the * argument in the argument list. The first argument is referenced by * "{@code 1$}", the second by "{@code 2$}", etc. * * <p> Another way to reference arguments by position is to use the * {@code '<'} (<code>'\u003c'</code>) flag, which causes the argument for * the previous format specifier to be re-used. For example, the following two * statements would produce identical strings: * * <blockquote><pre> * Calendar c = ...; * String s1 = String.format("Duke's Birthday: %1$tm %1$te,%1$tY", c); * * String s2 = String.format("Duke's Birthday: %1$tm %<te,%<tY", c); * </pre></blockquote> * * <hr> * <h2><a id="detail">Details</a></h2> * * <p> This section is intended to provide behavioral details for formatting, * including conditions and exceptions, supported data types, localization, and * interactions between flags, conversions, and data types. For an overview of * formatting concepts, refer to the <a href="#summary">Summary</a> * * <p> Any characters not explicitly defined as conversions, date/time * conversion suffixes, or flags are illegal and are reserved for * future extensions. Use of such a character in a format string will * cause an {@link UnknownFormatConversionException} or {@link * UnknownFormatFlagsException} to be thrown. * * <p> If the format specifier contains a width or precision with an invalid * value or which is otherwise unsupported, then a {@link * IllegalFormatWidthException} or {@link IllegalFormatPrecisionException} * respectively will be thrown. Similarly, values of zero for an argument * index will result in an {@link IllegalFormatException}. * * <p> If a format specifier contains a conversion character that is not * applicable to the corresponding argument, then an {@link * IllegalFormatConversionException} will be thrown. * * <p> Values of <i>precision</i> must be in the range zero to * {@link Integer#MAX_VALUE}, inclusive, otherwise * {@link IllegalFormatPrecisionException} is thrown.</p> * * <p> Values of <i>width</i> must be in the range one to * {@link Integer#MAX_VALUE}, inclusive, otherwise * {@link IllegalFormatWidthException} will be thrown * Note that widths can appear to have a negative value, but the negative sign * is a <i>flag</i>. For example in the format string {@code "%-20s"} the * <i>width</i> is <i>20</i> and the <i>flag</i> is "-".</p> * * <p> Values of <i>index</i> must be in the range one to * {@link Integer#MAX_VALUE}, inclusive, otherwise * {@link IllegalFormatException} will be thrown.</p> * * <p> All specified exceptions may be thrown by any of the {@code format} * methods of {@code Formatter} as well as by any {@code format} convenience * methods such as {@link String#format(String,Object...) String.format} and * {@link java.io.PrintStream#printf(String,Object...) PrintStream.printf}. * * <p> For category <i>General</i>, <i>Character</i>, <i>Numeric</i>, * <i>Integral</i> and <i>Date/Time</i> conversion, unless otherwise specified, * if the argument <i>arg</i> is {@code null}, then the result is "{@code null}". * * <p> Conversions denoted by an upper-case character (i.e. {@code 'B'}, * {@code 'H'}, {@code 'S'}, {@code 'C'}, {@code 'X'}, {@code 'E'}, * {@code 'G'}, {@code 'A'}, and {@code 'T'}) are the same as those for the * corresponding lower-case conversion characters except that the result is * converted to upper case according to the rules of the prevailing {@link * java.util.Locale Locale}. If there is no explicit locale specified, * either at the construction of the instance or as a parameter to its method * invocation, then the {@link java.util.Locale.Category#FORMAT default locale} * is used. * * <h3><a id="dgen">General</a></h3> * * <p> The following general conversions may be applied to any argument type: * * <table class="striped"> * <caption style="display:none">dgConv</caption> * <thead> * <tr><th scope="col" style="vertical-align:bottom"> Conversion * <th scope="col" style="vertical-align:bottom"> Unicode * <th scope="col" style="vertical-align:bottom"> Description * </thead> * <tbody> * * <tr><th scope="row" style="vertical-align:top"> {@code 'b'} * <td style="vertical-align:top"> <code>'\u0062'</code> * <td> Produces either "{@code true}" or "{@code false}" as returned by * {@link Boolean#toString(boolean)}. * * <p> If the argument is {@code null}, then the result is * "{@code false}". If the argument is a {@code boolean} or {@link * Boolean}, then the result is the string returned by {@link * String#valueOf(boolean) String.valueOf()}. Otherwise, the result is * "{@code true}". * * <p> If the {@code '#'} flag is given, then a {@link * FormatFlagsConversionMismatchException} will be thrown. * * <tr><th scope="row" style="vertical-align:top"> {@code 'B'} * <td style="vertical-align:top"> <code>'\u0042'</code> * <td> The upper-case variant of {@code 'b'}. * * <tr><th scope="row" style="vertical-align:top"> {@code 'h'} * <td style="vertical-align:top"> <code>'\u0068'</code> * <td> Produces a string representing the hash code value of the object. * * <p> The result is obtained by invoking * {@code Integer.toHexString(arg.hashCode())}. * * <p> If the {@code '#'} flag is given, then a {@link * FormatFlagsConversionMismatchException} will be thrown. * * <tr><th scope="row" style="vertical-align:top"> {@code 'H'} * <td style="vertical-align:top"> <code>'\u0048'</code> * <td> The upper-case variant of {@code 'h'}. * * <tr><th scope="row" style="vertical-align:top"> {@code 's'} * <td style="vertical-align:top"> <code>'\u0073'</code> * <td> Produces a string. * * <p> If the argument implements {@link Formattable}, then * its {@link Formattable#formatTo formatTo} method is invoked. * Otherwise, the result is obtained by invoking the argument's * {@code toString()} method. * * <p> If the {@code '#'} flag is given and the argument is not a {@link * Formattable}, then a {@link FormatFlagsConversionMismatchException} * will be thrown. * * <tr><th scope="row" style="vertical-align:top"> {@code 'S'} * <td style="vertical-align:top"> <code>'\u0053'</code> * <td> The upper-case variant of {@code 's'}. * * </tbody> * </table> * * <p> The following <a id="dFlags">flags</a> apply to general conversions: * * <table class="striped"> * <caption style="display:none">dFlags</caption> * <thead> * <tr><th scope="col" style="vertical-align:bottom"> Flag * <th scope="col" style="vertical-align:bottom"> Unicode * <th scope="col" style="vertical-align:bottom"> Description * </thead> * <tbody> * * <tr><th scope="row" style="vertical-align:top"> {@code '-'} * <td style="vertical-align:top"> <code>'\u002d'</code> * <td> Left justifies the output. Spaces (<code>'\u0020'</code>) will be * added at the end of the converted value as required to fill the minimum * width of the field. If the width is not provided, then a {@link * MissingFormatWidthException} will be thrown. If this flag is not given * then the output will be right-justified. * * <tr><th scope="row" style="vertical-align:top"> {@code '#'} * <td style="vertical-align:top"> <code>'\u0023'</code> * <td> Requires the output use an alternate form. The definition of the * form is specified by the conversion. * * </tbody> * </table> * * <p> The <a id="genWidth">width</a> is the minimum number of characters to * be written to the * output. If the length of the converted value is less than the width then * the output will be padded by <code>' '</code> (<code>'\u0020'</code>) * until the total number of characters equals the width. The padding is on * the left by default. If the {@code '-'} flag is given, then the padding * will be on the right. If the width is not specified then there is no * minimum. * * <p> The precision is the maximum number of characters to be written to the * output. The precision is applied before the width, thus the output will be * truncated to {@code precision} characters even if the width is greater than * the precision. If the precision is not specified then there is no explicit * limit on the number of characters. * * <h3><a id="dchar">Character</a></h3> * * This conversion may be applied to {@code char} and {@link Character}. It * may also be applied to the types {@code byte}, {@link Byte}, * {@code short}, and {@link Short}, {@code int} and {@link Integer} when * {@link Character#isValidCodePoint} returns {@code true}. If it returns * {@code false} then an {@link IllegalFormatCodePointException} will be * thrown. * * <table class="striped"> * <caption style="display:none">charConv</caption> * <thead> * <tr><th scope="col" style="vertical-align:bottom"> Conversion * <th scope="col" style="vertical-align:bottom"> Unicode * <th scope="col" style="vertical-align:bottom"> Description * </thead> * <tbody> * * <tr><th scope="row" style="vertical-align:top"> {@code 'c'} * <td style="vertical-align:top"> <code>'\u0063'</code> * <td> Formats the argument as a Unicode character as described in <a * href="../lang/Character.html#unicode">Unicode Character * Representation</a>. This may be more than one 16-bit {@code char} in * the case where the argument represents a supplementary character. * * <p> If the {@code '#'} flag is given, then a {@link * FormatFlagsConversionMismatchException} will be thrown. * * <tr><th scope="row" style="vertical-align:top"> {@code 'C'} * <td style="vertical-align:top"> <code>'\u0043'</code> * <td> The upper-case variant of {@code 'c'}. * * </tbody> * </table> * * <p> The {@code '-'} flag defined for <a href="#dFlags">General * conversions</a> applies. If the {@code '#'} flag is given, then a {@link * FormatFlagsConversionMismatchException} will be thrown. * * <p> The width is defined as for <a href="#genWidth">General conversions</a>. * * <p> The precision is not applicable. If the precision is specified then an * {@link IllegalFormatPrecisionException} will be thrown. * * <h3><a id="dnum">Numeric</a></h3> * * <p> Numeric conversions are divided into the following categories: * * <ol> * * <li> <a href="#dnint"><b>Byte, Short, Integer, and Long</b></a> * * <li> <a href="#dnbint"><b>BigInteger</b></a> * * <li> <a href="#dndec"><b>Float and Double</b></a> * * <li> <a href="#dnbdec"><b>BigDecimal</b></a> * * </ol> * * <p> Numeric types will be formatted according to the following algorithm: * * <p><b><a id="L10nAlgorithm"> Number Localization Algorithm</a></b> * * <p> After digits are obtained for the integer part, fractional part, and * exponent (as appropriate for the data type), the following transformation * is applied: * * <ol> * * <li> Each digit character <i>d</i> in the string is replaced by a * locale-specific digit computed relative to the current locale's * {@linkplain java.text.DecimalFormatSymbols#getZeroDigit() zero digit} * <i>z</i>; that is <i>d - </i> {@code '0'} * <i> + z</i>. * * <li> If a decimal separator is present, a locale-specific {@linkplain * java.text.DecimalFormatSymbols#getDecimalSeparator decimal separator} is * substituted. * * <li> If the {@code ','} (<code>'\u002c'</code>) * <a id="L10nGroup">flag</a> is given, then the locale-specific {@linkplain * java.text.DecimalFormatSymbols#getGroupingSeparator grouping separator} is * inserted by scanning the integer part of the string from least significant * to most significant digits and inserting a separator at intervals defined by * the locale's {@linkplain java.text.DecimalFormat#getGroupingSize() grouping * size}. * * <li> If the {@code '0'} flag is given, then the locale-specific {@linkplain * java.text.DecimalFormatSymbols#getZeroDigit() zero digits} are inserted * after the sign character, if any, and before the first non-zero digit, until * the length of the string is equal to the requested field width. * * <li> If the value is negative and the {@code '('} flag is given, then a * {@code '('} (<code>'\u0028'</code>) is prepended and a {@code ')'} * (<code>'\u0029'</code>) is appended. * * <li> If the value is negative (or floating-point negative zero) and * {@code '('} flag is not given, then a {@code '-'} (<code>'\u002d'</code>) * is prepended. * * <li> If the {@code '+'} flag is given and the value is positive or zero (or * floating-point positive zero), then a {@code '+'} (<code>'\u002b'</code>) * will be prepended. * * </ol> * * <p> If the value is NaN or positive infinity the literal strings "NaN" or * "Infinity" respectively, will be output. If the value is negative infinity, * then the output will be "(Infinity)" if the {@code '('} flag is given * otherwise the output will be "-Infinity". These values are not localized. * * <p><a id="dnint"><b> Byte, Short, Integer, and Long </b></a> * * <p> The following conversions may be applied to {@code byte}, {@link Byte}, * {@code short}, {@link Short}, {@code int} and {@link Integer}, * {@code long}, and {@link Long}. * * <table class="striped"> * <caption style="display:none">IntConv</caption> * <thead> * <tr><th scope="col" style="vertical-align:bottom"> Conversion * <th scope="col" style="vertical-align:bottom"> Unicode * <th scope="col" style="vertical-align:bottom"> Description * </thead> * <tbody> * * <tr><th scope="row" style="vertical-align:top"> {@code 'd'} * <td style="vertical-align:top"> <code>'\u0064'</code> * <td> Formats the argument as a decimal integer. The <a * href="#L10nAlgorithm">localization algorithm</a> is applied. * * <p> If the {@code '0'} flag is given and the value is negative, then * the zero padding will occur after the sign. * * <p> If the {@code '#'} flag is given then a {@link * FormatFlagsConversionMismatchException} will be thrown. * * <tr><th scope="row" style="vertical-align:top"> {@code 'o'} * <td style="vertical-align:top"> <code>'\u006f'</code> * <td> Formats the argument as an integer in base eight. No localization * is applied. * * <p> If <i>x</i> is negative then the result will be an unsigned value * generated by adding 2<sup>n</sup> to the value where {@code n} is the * number of bits in the type as returned by the static {@code SIZE} field * in the {@linkplain Byte#SIZE Byte}, {@linkplain Short#SIZE Short}, * {@linkplain Integer#SIZE Integer}, or {@linkplain Long#SIZE Long} * classes as appropriate. * * <p> If the {@code '#'} flag is given then the output will always begin * with the radix indicator {@code '0'}. * * <p> If the {@code '0'} flag is given then the output will be padded * with leading zeros to the field width following any indication of sign. * * <p> If {@code '('}, {@code '+'}, ' ', or {@code ','} flags * are given then a {@link FormatFlagsConversionMismatchException} will be * thrown. * * <tr><th scope="row" style="vertical-align:top"> {@code 'x'} * <td style="vertical-align:top"> <code>'\u0078'</code> * <td> Formats the argument as an integer in base sixteen. No * localization is applied. * * <p> If <i>x</i> is negative then the result will be an unsigned value * generated by adding 2<sup>n</sup> to the value where {@code n} is the * number of bits in the type as returned by the static {@code SIZE} field * in the {@linkplain Byte#SIZE Byte}, {@linkplain Short#SIZE Short}, * {@linkplain Integer#SIZE Integer}, or {@linkplain Long#SIZE Long} * classes as appropriate. * * <p> If the {@code '#'} flag is given then the output will always begin * with the radix indicator {@code "0x"}. * * <p> If the {@code '0'} flag is given then the output will be padded to * the field width with leading zeros after the radix indicator or sign (if * present). * * <p> If {@code '('}, <code>' '</code>, {@code '+'}, or * {@code ','} flags are given then a {@link * FormatFlagsConversionMismatchException} will be thrown. * * <tr><th scope="row" style="vertical-align:top"> {@code 'X'} * <td style="vertical-align:top"> <code>'\u0058'</code> * <td> The upper-case variant of {@code 'x'}. The entire string * representing the number will be converted to {@linkplain * String#toUpperCase upper case} including the {@code 'x'} (if any) and * all hexadecimal digits {@code 'a'} - {@code 'f'} * (<code>'\u0061'</code> - <code>'\u0066'</code>). * * </tbody> * </table> * * <p> If the conversion is {@code 'o'}, {@code 'x'}, or {@code 'X'} and * both the {@code '#'} and the {@code '0'} flags are given, then result will * contain the radix indicator ({@code '0'} for octal and {@code "0x"} or * {@code "0X"} for hexadecimal), some number of zeros (based on the width), * and the value. * * <p> If the {@code '-'} flag is not given, then the space padding will occur * before the sign. * * <p> The following <a id="intFlags">flags</a> apply to numeric integral * conversions: * * <table class="striped"> * <caption style="display:none">intFlags</caption> * <thead> * <tr><th scope="col" style="vertical-align:bottom"> Conversion * <th scope="col" style="vertical-align:bottom"> Unicode * <th scope="col" style="vertical-align:bottom"> Description * </thead> * <tbody> * * <tr><th scope="row" style="vertical-align:top"> {@code '+'} * <td style="vertical-align:top"> <code>'\u002b'</code> * <td> Requires the output to include a positive sign for all positive * numbers. If this flag is not given then only negative values will * include a sign. * * <p> If both the {@code '+'} and <code>' '</code> flags are given * then an {@link IllegalFormatFlagsException} will be thrown. * * <tr><th scope="row" style="vertical-align:top"> <code>' '</code> * <td style="vertical-align:top"> <code>'\u0020'</code> * <td> Requires the output to include a single extra space * (<code>'\u0020'</code>) for non-negative values. * * <p> If both the {@code '+'} and <code>' '</code> flags are given * then an {@link IllegalFormatFlagsException} will be thrown. * * <tr><th scope="row" style="vertical-align:top"> {@code '0'} * <td style="vertical-align:top"> <code>'\u0030'</code> * <td> Requires the output to be padded with leading {@linkplain * java.text.DecimalFormatSymbols#getZeroDigit zeros} to the minimum field * width following any sign or radix indicator except when converting NaN * or infinity. If the width is not provided, then a {@link * MissingFormatWidthException} will be thrown. * * <p> If both the {@code '-'} and {@code '0'} flags are given then an * {@link IllegalFormatFlagsException} will be thrown. * * <tr><th scope="row" style="vertical-align:top"> {@code ','} * <td style="vertical-align:top"> <code>'\u002c'</code> * <td> Requires the output to include the locale-specific {@linkplain * java.text.DecimalFormatSymbols#getGroupingSeparator group separators} as * described in the <a href="#L10nGroup">"group" section</a> of the * localization algorithm. * * <tr><th scope="row" style="vertical-align:top"> {@code '('} * <td style="vertical-align:top"> <code>'\u0028'</code> * <td> Requires the output to prepend a {@code '('} * (<code>'\u0028'</code>) and append a {@code ')'} * (<code>'\u0029'</code>) to negative values. * * </tbody> * </table> * * <p> If no <a id="intdFlags">flags</a> are given the default formatting is * as follows: * * <ul> * * <li> The output is right-justified within the {@code width} * * <li> Negative numbers begin with a {@code '-'} (<code>'\u002d'</code>) * * <li> Positive numbers and zero do not include a sign or extra leading * space * * <li> No grouping separators are included * * </ul> * * <p> The <a id="intWidth">width</a> is the minimum number of characters to * be written to the output. This includes any signs, digits, grouping * separators, radix indicator, and parentheses. If the length of the * converted value is less than the width then the output will be padded by * spaces (<code>'\u0020'</code>) until the total number of characters equals * width. The padding is on the left by default. If {@code '-'} flag is * given then the padding will be on the right. If width is not specified then * there is no minimum. * * <p> The precision is not applicable. If precision is specified then an * {@link IllegalFormatPrecisionException} will be thrown. * * <p><a id="dnbint"><b> BigInteger </b></a> * * <p> The following conversions may be applied to {@link * java.math.BigInteger}. * * <table class="striped"> * <caption style="display:none">bIntConv</caption> * <thead> * <tr><th scope="col" style="vertical-align:bottom"> Conversion * <th scope="col" style="vertical-align:bottom"> Unicode * <th scope="col" style="vertical-align:bottom"> Description * </thead> * <tbody> * * <tr><th scope="row" style="vertical-align:top"> {@code 'd'} * <td style="vertical-align:top"> <code>'\u0064'</code> * <td> Requires the output to be formatted as a decimal integer. The <a * href="#L10nAlgorithm">localization algorithm</a> is applied. * * <p> If the {@code '#'} flag is given {@link * FormatFlagsConversionMismatchException} will be thrown. * * <tr><th scope="row" style="vertical-align:top"> {@code 'o'} * <td style="vertical-align:top"> <code>'\u006f'</code> * <td> Requires the output to be formatted as an integer in base eight. * No localization is applied. * * <p> If <i>x</i> is negative then the result will be a signed value * beginning with {@code '-'} (<code>'\u002d'</code>). Signed output is * allowed for this type because unlike the primitive types it is not * possible to create an unsigned equivalent without assuming an explicit * data-type size. * * <p> If <i>x</i> is positive or zero and the {@code '+'} flag is given * then the result will begin with {@code '+'} (<code>'\u002b'</code>). * * <p> If the {@code '#'} flag is given then the output will always begin * with {@code '0'} prefix. * * <p> If the {@code '0'} flag is given then the output will be padded * with leading zeros to the field width following any indication of sign. * * <p> If the {@code ','} flag is given then a {@link * FormatFlagsConversionMismatchException} will be thrown. * * <tr><th scope="row" style="vertical-align:top"> {@code 'x'} * <td style="vertical-align:top"> <code>'\u0078'</code> * <td> Requires the output to be formatted as an integer in base * sixteen. No localization is applied. * * <p> If <i>x</i> is negative then the result will be a signed value * beginning with {@code '-'} (<code>'\u002d'</code>). Signed output is * allowed for this type because unlike the primitive types it is not * possible to create an unsigned equivalent without assuming an explicit * data-type size. * * <p> If <i>x</i> is positive or zero and the {@code '+'} flag is given * then the result will begin with {@code '+'} (<code>'\u002b'</code>). * * <p> If the {@code '#'} flag is given then the output will always begin * with the radix indicator {@code "0x"}. * * <p> If the {@code '0'} flag is given then the output will be padded to * the field width with leading zeros after the radix indicator or sign (if * present). * * <p> If the {@code ','} flag is given then a {@link * FormatFlagsConversionMismatchException} will be thrown. * * <tr><th scope="row" style="vertical-align:top"> {@code 'X'} * <td style="vertical-align:top"> <code>'\u0058'</code> * <td> The upper-case variant of {@code 'x'}. The entire string * representing the number will be converted to {@linkplain * String#toUpperCase upper case} including the {@code 'x'} (if any) and * all hexadecimal digits {@code 'a'} - {@code 'f'} * (<code>'\u0061'</code> - <code>'\u0066'</code>). * * </tbody> * </table> * * <p> If the conversion is {@code 'o'}, {@code 'x'}, or {@code 'X'} and * both the {@code '#'} and the {@code '0'} flags are given, then result will * contain the base indicator ({@code '0'} for octal and {@code "0x"} or * {@code "0X"} for hexadecimal), some number of zeros (based on the width), * and the value. * * <p> If the {@code '0'} flag is given and the value is negative, then the * zero padding will occur after the sign. * * <p> If the {@code '-'} flag is not given, then the space padding will occur * before the sign. * * <p> All <a href="#intFlags">flags</a> defined for Byte, Short, Integer, and * Long apply. The <a href="#intdFlags">default behavior</a> when no flags are * given is the same as for Byte, Short, Integer, and Long. * * <p> The specification of <a href="#intWidth">width</a> is the same as * defined for Byte, Short, Integer, and Long. * * <p> The precision is not applicable. If precision is specified then an * {@link IllegalFormatPrecisionException} will be thrown. * * <p><a id="dndec"><b> Float and Double</b></a> * * <p> The following conversions may be applied to {@code float}, {@link * Float}, {@code double} and {@link Double}. * * <table class="striped"> * <caption style="display:none">floatConv</caption> * <thead> * <tr><th scope="col" style="vertical-align:bottom"> Conversion * <th scope="col" style="vertical-align:bottom"> Unicode * <th scope="col" style="vertical-align:bottom"> Description * </thead> * <tbody> * * <tr><th scope="row" style="vertical-align:top"> {@code 'e'} * <td style="vertical-align:top"> <code>'\u0065'</code> * <td> Requires the output to be formatted using <a * id="scientific">computerized scientific notation</a>. The <a * href="#L10nAlgorithm">localization algorithm</a> is applied. * * <p> The formatting of the magnitude <i>m</i> depends upon its value. * * <p> If <i>m</i> is NaN or infinite, the literal strings "NaN" or * "Infinity", respectively, will be output. These values are not * localized. * * <p> If <i>m</i> is positive-zero or negative-zero, then the exponent * will be {@code "+00"}. * * <p> Otherwise, the result is a string that represents the sign and * magnitude (absolute value) of the argument. The formatting of the sign * is described in the <a href="#L10nAlgorithm">localization * algorithm</a>. The formatting of the magnitude <i>m</i> depends upon its * value. * * <p> Let <i>n</i> be the unique integer such that 10<sup><i>n</i></sup> * <= <i>m</i> < 10<sup><i>n</i>+1</sup>; then let <i>a</i> be the * mathematically exact quotient of <i>m</i> and 10<sup><i>n</i></sup> so * that 1 <= <i>a</i> < 10. The magnitude is then represented as the * integer part of <i>a</i>, as a single decimal digit, followed by the * decimal separator followed by decimal digits representing the fractional * part of <i>a</i>, followed by the exponent symbol {@code 'e'} * (<code>'\u0065'</code>), followed by the sign of the exponent, followed * by a representation of <i>n</i> as a decimal integer, as produced by the * method {@link Long#toString(long, int)}, and zero-padded to include at * least two digits. * * <p> The number of digits in the result for the fractional part of * <i>m</i> or <i>a</i> is equal to the precision. If the precision is not * specified then the default value is {@code 6}. If the precision is less * than the number of digits which would appear after the decimal point in * the string returned by {@link Float#toString(float)} or {@link * Double#toString(double)} respectively, then the value will be rounded * using the {@linkplain java.math.RoundingMode#HALF_UP round half up * algorithm}. Otherwise, zeros may be appended to reach the precision. * For a canonical representation of the value, use {@link * Float#toString(float)} or {@link Double#toString(double)} as * appropriate. * * <p>If the {@code ','} flag is given, then an {@link * FormatFlagsConversionMismatchException} will be thrown. * * <tr><th scope="row" style="vertical-align:top"> {@code 'E'} * <td style="vertical-align:top"> <code>'\u0045'</code> * <td> The upper-case variant of {@code 'e'}. The exponent symbol * will be {@code 'E'} (<code>'\u0045'</code>). * * <tr><th scope="row" style="vertical-align:top"> {@code 'g'} * <td style="vertical-align:top"> <code>'\u0067'</code> * <td> Requires the output to be formatted in general scientific notation * as described below. The <a href="#L10nAlgorithm">localization * algorithm</a> is applied. * * <p> After rounding for the precision, the formatting of the resulting * magnitude <i>m</i> depends on its value. * * <p> If <i>m</i> is greater than or equal to 10<sup>-4</sup> but less * than 10<sup>precision</sup> then it is represented in <i><a * href="#decimal">decimal format</a></i>. * * <p> If <i>m</i> is less than 10<sup>-4</sup> or greater than or equal to * 10<sup>precision</sup>, then it is represented in <i><a * href="#scientific">computerized scientific notation</a></i>. * * <p> The total number of significant digits in <i>m</i> is equal to the * precision. If the precision is not specified, then the default value is * {@code 6}. If the precision is {@code 0}, then it is taken to be * {@code 1}. * * <p> If the {@code '#'} flag is given then an {@link * FormatFlagsConversionMismatchException} will be thrown. * * <tr><th scope="row" style="vertical-align:top"> {@code 'G'} * <td style="vertical-align:top"> <code>'\u0047'</code> * <td> The upper-case variant of {@code 'g'}. * * <tr><th scope="row" style="vertical-align:top"> {@code 'f'} * <td style="vertical-align:top"> <code>'\u0066'</code> * <td> Requires the output to be formatted using <a id="decimal">decimal * format</a>. The <a href="#L10nAlgorithm">localization algorithm</a> is * applied. * * <p> The result is a string that represents the sign and magnitude * (absolute value) of the argument. The formatting of the sign is * described in the <a href="#L10nAlgorithm">localization * algorithm</a>. The formatting of the magnitude <i>m</i> depends upon its * value. * * <p> If <i>m</i> NaN or infinite, the literal strings "NaN" or * "Infinity", respectively, will be output. These values are not * localized. * * <p> The magnitude is formatted as the integer part of <i>m</i>, with no * leading zeroes, followed by the decimal separator followed by one or * more decimal digits representing the fractional part of <i>m</i>. * * <p> The number of digits in the result for the fractional part of * <i>m</i> or <i>a</i> is equal to the precision. If the precision is not * specified then the default value is {@code 6}. If the precision is less * than the number of digits which would appear after the decimal point in * the string returned by {@link Float#toString(float)} or {@link * Double#toString(double)} respectively, then the value will be rounded * using the {@linkplain java.math.RoundingMode#HALF_UP round half up * algorithm}. Otherwise, zeros may be appended to reach the precision. * For a canonical representation of the value, use {@link * Float#toString(float)} or {@link Double#toString(double)} as * appropriate. * * <tr><th scope="row" style="vertical-align:top"> {@code 'a'} * <td style="vertical-align:top"> <code>'\u0061'</code> * <td> Requires the output to be formatted in hexadecimal exponential * form. No localization is applied. * * <p> The result is a string that represents the sign and magnitude * (absolute value) of the argument <i>x</i>. * * <p> If <i>x</i> is negative or a negative-zero value then the result * will begin with {@code '-'} (<code>'\u002d'</code>). * * <p> If <i>x</i> is positive or a positive-zero value and the * {@code '+'} flag is given then the result will begin with {@code '+'} * (<code>'\u002b'</code>). * * <p> The formatting of the magnitude <i>m</i> depends upon its value. * * <ul> * * <li> If the value is NaN or infinite, the literal strings "NaN" or * "Infinity", respectively, will be output. * * <li> If <i>m</i> is zero then it is represented by the string * {@code "0x0.0p0"}. * * <li> If <i>m</i> is a {@code double} value with a normalized * representation then substrings are used to represent the significand and * exponent fields. The significand is represented by the characters * {@code "0x1."} followed by the hexadecimal representation of the rest * of the significand as a fraction. The exponent is represented by * {@code 'p'} (<code>'\u0070'</code>) followed by a decimal string of the * unbiased exponent as if produced by invoking {@link * Integer#toString(int) Integer.toString} on the exponent value. If the * precision is specified, the value is rounded to the given number of * hexadecimal digits. * * <li> If <i>m</i> is a {@code double} value with a subnormal * representation then, unless the precision is specified to be in the range * 1 through 12, inclusive, the significand is represented by the characters * {@code '0x0.'} followed by the hexadecimal representation of the rest of * the significand as a fraction, and the exponent represented by * {@code 'p-1022'}. If the precision is in the interval * [1, 12], the subnormal value is normalized such that it * begins with the characters {@code '0x1.'}, rounded to the number of * hexadecimal digits of precision, and the exponent adjusted * accordingly. Note that there must be at least one nonzero digit in a * subnormal significand. * * </ul> * * <p> If the {@code '('} or {@code ','} flags are given, then a {@link * FormatFlagsConversionMismatchException} will be thrown. * * <tr><th scope="row" style="vertical-align:top"> {@code 'A'} * <td style="vertical-align:top"> <code>'\u0041'</code> * <td> The upper-case variant of {@code 'a'}. The entire string * representing the number will be converted to upper case including the * {@code 'x'} (<code>'\u0078'</code>) and {@code 'p'} * (<code>'\u0070'</code> and all hexadecimal digits {@code 'a'} - * {@code 'f'} (<code>'\u0061'</code> - <code>'\u0066'</code>). * * </tbody> * </table> * * <p> All <a href="#intFlags">flags</a> defined for Byte, Short, Integer, and * Long apply. * * <p> If the {@code '#'} flag is given, then the decimal separator will * always be present. * * <p> If no <a id="floatdFlags">flags</a> are given the default formatting * is as follows: * * <ul> *
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