Format Specifiers in Java

Format specifiers begin with a percent character (%) and terminate with a "type character, " which indicates the type of data (int, float, etc.) that will be converted the basic manner in which the data will be represented (decimal, hexadecimal, etc.) The general syntax of a format specifier is

% [flags] [width] [.precision] [argsize] typechar

The format() method of Formatter class accepts a wide variety of format specifiers. When an uppercase specifier is used, then letters are shown in uppercase. Otherwise, the upper- and lowercase specifiers perform the same conversion. 
 

• Space format specifier : When creating columns of numbers, it is sometimes very useful to print a space before a positive number so that positive and negative number get aligned. To do this, space format specifier can be used. Syntax:

Formatter().format("% d", -111);
Formatter().format("% d", 111);

Output:
-111
 111

Example: 

-111
 111
-222
 222

• + Sign Specifier: This adds the + sign before positive numeric value, and has no effect on negative numeric value. Syntax:

Formatter().format("%+d", 111);

Output:
+111

Example: 

+111
-111

• ( specifier: This specifier puts the negative numeric values inside the parentheses, and has no effect on the positive numeric values. Syntax:

Formatter().format("%(d", -111);
Formatter().format("%(d", 111);

Output:
(111)
111

Example: 

(111)
111

• Comma, Specifier: For displaying large numbers, it is often useful to add grouping separators by comma (, ). For example, the value is 1000000 more easily read when formatted as 1, 000, 000. To add grouping specifiers (, ) use the comma(, ) Specifier. Syntax:

Formatter().format("%, d", 1000000);

Output:
1, 000, 000

Example: 

1, 000, 000
32, 659, 526, 566.452

• Left Justification(-) Specifier: By default all output is right-shifted. That is, if the field width is longer than the data printed, data will be placed on the right side of the field. One can force output to be left-justified by placing a minus sign directly after the %. For instance, %-20.4f left justifies a floating-point number with two decimal places in a 20-character field. Syntax:

Formatter().format("|%-20.4f|", 1234.1234);

Output:
| 1234.1234|
|1234.1234 |

Example: 

| 1234.1234|
|1234.1234 |

• The %n format specifiers: The %n format specifier is different from the others in that it doesn't take arguments. It is simply an escape sequence that inserts a character into the output. The %n inserts a newline. It can't be entered directly into the format string. 

Geeks 
For 
Geeks

• The %% format specifiers: The %% format specifier is different from the others in that it doesn't take arguments. It is simply an escape sequence that inserts a character into the output. The %% inserts a % sign. It can't be entered directly into the format string. 

10 % 4 = 2

• The %x %X format specifiers: The %x or %X format specifier is used to represent the integer Hexadecimal value. %x displays the hexadecimal values with lowercase alphabets whereas the %X specifier displays the hexadecimal values with uppercase alphabets. 

LowerCase Hexadecimal using %x: fa
UpperCase Hexadecimal using %X: FA

• The %e %E format specifiers: The %e or %E format specifier  is used to represent the Scientific Notation of a value. %e displays the Scientific Notation with lowercase alphabets whereas the %E specifier displays the Scientific Notation with uppercase alphabets. 

LowerCase Scientific Notation using %e: 1.231234e+02
UpperCase Scientific Notation using %E: 1.231234E+02

• Precision Formats A precision specifier can be applied to the %f, %e, %g, and %s format specifiers. 

Scientific notation to 2 places: 1.23e+02
Decimal floating-point notation to 4 places: 123.1235
Scientific or Decimal floating-point notation to 4 places: 123.1
String notation to 15 places: 123456789012345
value in 10 digits: 0000000088

Related Article : Format Specifiers in C