There are times when you need to present a stored value in a different format . . . 

Real number example –  8.987578. Here you may prefer to say 8.99

Date example – “2018-1-1”. Here you may prefer to say “1 January 2018”

Java has a number of String formatting methods that do not alter the original value but allows you to express the value in a different format.

Shown below are two examples i.e. one that allows you to format a real number differently and another that allows you to format a date differently. Both of these format methods allow you to define the format using a String parameter.


 // Formatting real numbers and dates for output in another format.
 // Using String as a parameter to define an output format.
 // New output format does not affect the original value in any way.
// // Default date format is yyyy-MM-dd // Other formats include . . . // "yyyy/M/dd" Month as a single digit. // "dd-MMM-yyyy" Month as 3 letters. // "dd-MMMM-yyyy" Month in full as letters. // "dd-MM-yy"
 import java.text.DecimalFormat;
 import java.time.format.DateTimeFormatter;
 import java.time.*;

public class Formatting {

public static void main (String[]args) {

// Define the desired format as a String and apply the format
 DecimalFormat d = new DecimalFormat("0.000");
 double theDouble = 45.78864469;

// Define the desired format as a String and apply the format
 DateTimeFormatter formatDate = DateTimeFormatter.ofPattern("dd-MMMM-yyyy");
 LocalDate localDate = LocalDate.of(2021, 11, 19);
 String localDateString = formatDate.format(localDate);