Java printf method

The printf method in Java can be used to write a formatted string to the console with different format options. It is also a method of the PrintStream.

Syntax available for printf()

System.out.printf(string);
System.out.printf(format, arguments);
System.out.printf(locale, format, arguments);

 

Format specifiers

 

Format specifiers always start with “%”, following the ‘%’ sign, a format specifier includes flags

%<flags><width><.precision>conversion-character

 

Although, all the specifiers mentioned in the brackets are optional, format specifier consists of % accompanied with a conversion character

 

• The  define the standard ways for modifying the output. it is also a common way for formatting integers and floating-point numbers.

• The specifies the length of the field for printing the argument

• The <.precision> specifies the number of digits of precision when printing a floating-point value

• A conversion character determines how the argument will be formatted

 

Specifier	Explanation
%c	Format characters
%n	add a new line character
%o	Format octal numbers (base 8)
%d	Format decimal (integer) numbers (base 10)
%i	Format integers (base 10)
%x	Format numbers in hexadecimal (base 16)
%e	Format exponential floating-point numbers
%s	Format string of characters
%u	Format unsigned decimal (integer) numbers
%f	Format floating-point numbers

 

Example

 

1.String Formating:

we use the %s or %S when it comes to formatting strings using printf in Java,

System.out.printf("%s%n", "hello world!");
System.out.printf("'%S' %n", "hello world!");

output:

hello world!
'HELLO WORLD!'

 

2.formating Integer:

With the use %d specifier you can format any type of integer available in java e.g byte, short, int, long

System.out.printf("it is an integer: %d%n", 10000);

output

it is an integer: 10000

Output can also be formatted for different locales by overloading the method with the local parameter.

System.out.printf(Locale.US, "%,d %n", 12300);
System.out.printf(Locale.ITALY, "%,d %n", 10000);

output:

12,300
10.000

 

3.Formatting floating numbers and doubles:

To format a float number, you have to use the %f  specifier

System.out.printf("%f%n", 3.1423);

output:

3.142300

EX

System.out.printf("'%3.2f'%n", 3.1423);

Now the minimum width of our floating number will be 3, and the length of the decimal part will be 2 so the output will be

3.15

 

4.Formatting a Boolean value

To format Boolean values, we use the %b  format specifier

boolean adult = true; 
boolean member = false;
  System.out.printf(“%b%n”, adult);
 System.out.printf("%b%n", member);

The output will be:

true
false