Java Formatter Class

In this chapter you will learn:

1. What is Java Format Class
2. Syntax for format method
3. Note for format method
4. Example - format method

Description

Formatter class outputs the formatted output. It can format numbers, strings, and time and date. It operates in a manner similar to the C/C++ printf() function.

Syntax

The most commonly used format function is:

Formatter format(String fmtString, Object ... args)

Note

The fmtSring consists characters that are copied to the output buffer and the format specifiers.

A format specifier begins with a percent sign followed by the format conversion specifier. For example, the format specifier for floating-point data is

The format specifiers and the arguments are matched in order from left to right.

Example

For example, consider this fragment:

import java.util.Formatter;
/* ww  w  .  j  ava2 s  .c  o  m*/
public class Main {
  public static void main(String args[]) {
    Formatter fmt = new Formatter();
    fmt.format("%s gap filler %d %f", "Astring", 10, 12.3); 
    System.out.println(fmt.out());
  }
}

The output:

In this example, the format specifiers, %s, %d, and %f, are replaced with the arguments that follow the format string. %s is replaced by "Astring", %d is replaced by 10, and %f is replaced by 12.3. %s specifies a string, and %d specifies an integer value. %f specifies a floating-point value. All other characters are simply used as-is.

Next chapter...

What you will learn in the next chapter:

1. What is Format Specifier
2. What are the specifiers for Java Formatter class
3. Example - Java Format Specifier
4. Example - Unknown Format Conversion Exception
5. How to use %n and %% specifiers to escape new line and percentage
6. Example - The following code combines the %n, %d %% to display file copy progress information

Java Formatter Class