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Java String format() method

by Online Tutorials Library July 22, 2022

Java String format()

The java string format() method returns the formatted string by given locale, format and arguments.

If you don’t specify the locale in String.format() method, it uses default locale by calling Locale.getDefault() method.

The format() method of java language is like sprintf() function in c language and printf() method of java language.

Internal implementation

 public static String format(String format, Object… args) {         return new Formatter().format(format, args).toString();     } 

Signature

There are two type of string format() method:

 public static String format(String format, Object… args) and, public static String format(Locale locale, String format, Object… args) 

Parameters

locale : specifies the locale to be applied on the format() method.

format : format of the string.

args : arguments for the format string. It may be zero or more.

Returns

formatted string

Throws

NullPointerException : if format is null.

IllegalFormatException : if format is illegal or incompatible.

Java String format() method example

 public class FormatExample{ public static void main(String args[]){ String name=”Tutoraspire”; String sf1=String.format(“name is %s”,name); String sf2=String.format(“value is %f”,32.33434); String sf3=String.format(“value is %32.12f”,32.33434);//returns 12 char fractional part filling with 0  System.out.println(sf1); System.out.println(sf2); System.out.println(sf3); }} 

name is amit singh value is 32.334340 value is                  32.334340000000

Java String Format Specifiers

Here, we are providing a table of format specifiers supported by the Java String.

Format Specifier	Data Type	Output
%a	floating point (except BigDecimal)	Returns Hex output of floating point number.
%b	Any type	“true” if non-null, “false” if null
%c	character	Unicode character
%d	integer (incl. byte, short, int, long, bigint)	Decimal Integer
%e	floating point	decimal number in scientific notation
%f	floating point	decimal number
%g	floating point	decimal number, possibly in scientific notation depending on the precision and value.
%h	any type	Hex String of value from hashCode() method.
%n	none	Platform-specific line separator.
%o	integer (incl. byte, short, int, long, bigint)	Octal number
%s	any type	String value
%t	Date/Time (incl. long, Calendar, Date and TemporalAccessor)	%t is the prefix for Date/Time conversions. More formatting flags are needed after this. See Date/Time conversion below.
%x	integer (incl. byte, short, int, long, bigint)	Hex string.

Java String format() Method Example 2

This method supports various data types and formats them into a string type. Let us see an example.

 public class FormatExample2 { public static void main(String[] args) { String str1 = String.format(“%d”, 101);  // Integer value String str2 = String.format(“%s”, “Amar Singh”); // String value String str3 = String.format(“%f”, 101.00);       // Float value String str4 = String.format(“%x”, 101);          // Hexadecimal value String str5 = String.format(“%c”, ‘c’);          // Char value System.out.println(str1); System.out.println(str2); System.out.println(str3); System.out.println(str4); System.out.println(str5); }  } 

101 Amar Singh 101.000000 65 c

Java String format() Method Example 3

Apart from formatting, we can set width, padding etc. of any value. Let us see an example where we are setting width and padding for an integer value.

 public class FormatExample3 { public static void main(String[] args) { String str1 = String.format(“%d”, 101); String str2 = String.format(“|%10d|”, 101);  // Specifying length of integer String str3 = String.format(“|%-10d|”, 101); // Left-justifying within the specified width String str4 = String.format(“|% d|”, 101);  String str5 = String.format(“|%010d|”, 101); // Filling with zeroes System.out.println(str1); System.out.println(str2); System.out.println(str3); System.out.println(str4); System.out.println(str5); } } 

101 |       101| |101       | | 101| |0000000101|

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