Formatting Data - Beginning Java 8 Fundamentals - page 496

Using Flags in a Format Specifier
Flags act as modifiers. They modify the formatted output. Table 13-3 lists all flags that can be used in a format specifier.

Table 13-3. List of Valid Flags, Their Descriptions, and Examples of Their Usage

Flag Description Examples

Format String Argument Formatted Text

'-' The result is left justified. Note that

the result is right justified when you do
not use the '-' flag in a format specifier.

“'%6s'” “Ken” ' Ken'

“'%-6s'” “Ken” 'Ken '

'#' The argument is formatted in alternate

form depending on the conversion part
of the format specifier. The example
shows the same decimal number, 6270185,
being formatted to a hexadecimal format.
When '#' flag is used, the hexadecimal number
is prefixed with “0x”.

“%x” 6270185 5face9

“%#x” 6270185 0x5face9

'+' The result contains a + sign for positive

values. It applies only to numeric values.

“%d” 105 105

“%+d” 105 +105

' ' The result contains a leading space

for positive values. It applies only to
numeric values.

“'%d'” 105 '105'

“'% d'” 105 ' 105'

'0' The result is zero padded. It applies

only to numeric values.

“'%6d'” 105 ' 105'

“'%06d'” 105 '000105'

' , ' The result contains a locale-specific

grouping separator. It applied only to
numeric values. For example, a comma is
used as a thousand-separator in US locale,
whereas a space is used in France locale.

“%,d” 89105 89,105 (US Locale)

“%,d” 89105 89 105 (France locale)

'(' The result is enclosed in

parentheses for a negative number.
It applies only to numeric values.

“%d” -1969 -1969

“%(d” -1969 (1969)

'<' It causes the argument for the previous

format specifier to be reused. It is mostly
used in formatting dates and times.

“%s and %<s” “Ken” Ken and Ken

The valid use of a flag depends on the context of its use. Depending on the value being formatted, it is allowed to
use multiple flags in a format specifier. For example, the format specifier "%1$,0(12d" uses three flags: ',' , '0' , and
'(' . If -122899 is used as the argument by this format specifier, it will output (000122,899) . The effects of using each
flag will be discussed in detail when I discuss formatting for different data types in the sections to follow.