.printf()

The .printf() method prints output to the console with the use of various formatting commands.

System.out.printf(formatstring, arg1, arg2, ... argN);

Where formatstring is a string containing various format commands defining how to print an arbitrary number of additional arguments, arg1, arg2, ... argN. The format string contains text which is rendered as it appears in the string and format specifiers that output an argument in a specified format.

Format Specifiers

Format specifiers obey the following sequence:

%[index$][flags][width][.precision]conversion-character

The elements in square brackets ([...]) are optional.

index$ is a number followed by $ which specifies the index of the argument being formatted. The default is to format arguments in the order they appear.

flags can contain one or more of the following characters:

• -: Left-justify. Defaults to right-justify.
• +: For numerical values display a leading + or -.
• 0: Zero-pad numerical values (blank padding is the default).
• ,: Use a comma grouping separator for numerical values (i.e., 1,000,000).
• A space will show a leading - for negative numbers or a space for positive numbers.

width is a number representing the minimum width used for outputting characters.

precision is a number representing the number of digits used to the right of the decimal for floating point numbers, or the length of a substring to extract from a string.

conversion-characters are one of the following:

• b: Boolean value.
• B: Boolean value, uppercase.
• c: Unicode character.
• C: Unicode character, force uppercase.
• d: Decimal integer.
• f: Floating-point number.
• h: Hashcode.
• n: Newline character, platform specific.
• s: String.
• S: String, force uppercase.
• t: Time/date formatting.

The t time/date character is followed by one of the following characters to extract parts of a datetime value:

• T: Time in hh:mm:ss format.
• H: Hour.
• M: Minute.
• S: Second.
• L: Millisecond.
• N: Nanosecond.
• p: A.M./P.M.
• z: Time zone offset.
• A: Full day of the week.
• d: Two digit day of the month.
• B: Full month name.
• m: Two-digit month.
• Y: Four-digit year.
• y: Last two digits of year.

The following example uses .printf() to format various types of output.

import java.util.*;

public class PrintExample {
  public static void main(String[] args) {
    System.out.printf("This is a string: '%10s'%n", "Output");
    System.out.printf("This is a float: %+.2f%n", 123.456);
    Date date = new Date();
    System.out.printf("This is a date: %1$tA, %1$tB %1$td %1$tY %n", date);
  }
}

This will produce the following output (with the current date):

This is a string: '    Output'
This is a float: +123.46
This is a date: Saturday, June 11 2022