Formatted output in Java

Sometimes in Competitive programming, it is essential to print the output in a given specified format. Most users are familiar with printf function in C. Let us see discuss how we can format the output in Java:

Formatting output using System.out.printf()
This is the easiest of all methods as this is similar to printf in C. Note that System.out.print() and System.out.println() take a single argument, but printf() may take multiple arguments.

// A Java program to demonstrate working of printf() in Java 
class JavaFormatter1 
{ 
  public static void main(String args[]) 
  { 
    int x = 100; 
    System.out.printf("Printing simple integer: x = %d\n", x); 
  
    // this will print it upto 2 decimal places 
    System.out.printf("Formatted with precison: PI = %.2f\n", Math.PI); 
  
    float n = 5.2f; 
  
    // automatically appends zero to the rightmost part of decimal 
    System.out.printf("Formatted to specific width: n = %.4f\n", n); 
  
    n = 2324435.3f; 
  
    // here number is formatted from right margin and occupies a 
    // width of 20 characters 
    System.out.printf("Formatted to right margin: n = %20.4f\n", n); 
  } 
} 

Output:

Printing simple integer: x = 100
Formatted with precison: PI = 3.14
Formatted to specific width: n = 5.2000
Formatted to right margin: n =         2324435.2500

System.out.format() is equivalent to printf() and can also be used.

Formatting using DecimalFormat class:
DecimalFormat is used to format decimal numbers.

// Java program to demonstrate working of DecimalFormat 
import java.text.DecimalFormat; 
  
class JavaFormatter2 
{ 
  public static void main(String args[]) 
  { 
    double num = 123.4567; 
  
    // prints only numeric part of a floating number 
    DecimalFormat ft = new DecimalFormat("####"); 
    System.out.println("Without fraction part: num = " + ft.format(num)); 
  
    // this will print it upto 2 decimal places 
    ft = new DecimalFormat("#.##"); 
    System.out.println("Formatted to Give precison: num = " + ft.format(num)); 
  
    // automatically appends zero to the rightmost part of decimal 
    // instead of #,we use digit 0 
    ft = new DecimalFormat("#.000000"); 
    System.out.println("appended zeroes to right: num = " + ft.format(num)); 
  
    // automatically appends zero to the leftmost of decimal number 
    // instead of #,we use digit 0 
    ft = new DecimalFormat("00000.00"); 
    System.out.println("formatting Numeric part : num = "+ft.format(num)); 
  
    // formatting money in dollars 
    double income = 23456.789; 
    ft = new DecimalFormat("$###,###.##"); 
    System.out.println("your Formatted Dream Income : " + ft.format(income)); 
  } 
} 

Output:

Without fraction part: num = 123
Formatted to Give precison: num = 123.46
appended zeroes to right: num = 123.456700
formatting Numeric part : num = 00123.46
your Formatted Dream Income : $23,456.79

Formatting dates and parsing using SimpleDateFormat class:
This class is present in java.text package.

// Java program to demonstrate working of SimpleDateFormat 
import java.text.ParseException; 
import java.text.SimpleDateFormat; 
import java.util.Date; 
  
class Formatter3 
{ 
  public static void main(String args[]) throws ParseException 
  { 
    // Formatting as per given pattern in the argument 
    SimpleDateFormat ft = new SimpleDateFormat("dd-MM-yyyy"); 
    String str = ft.format(new Date()); 
    System.out.println("Formatted Date : " + str); 
  
    // parsing a given String 
    str = "02/18/1995"; 
    ft = new SimpleDateFormat("MM/dd/yyyy"); 
    Date date = ft.parse(str); 
  
    // this will print the date as per parsed string 
    System.out.println("Parsed Date : " + date); 
  } 
} 

Output:

Formatted Date : 09-08-2018
Parsed Date : Sat Feb 18 00:00:00 UTC 1995

References:
https://docs.oracle.com/javase/tutorial/essential/io/formatting.html
https://docs.oracle.com/javase/tutorial/java/data/numberformat.html
http://docs.oracle.com/javase/6/docs/api/java/text/SimpleDateFormat.html

This article is contributed by Pankaj Kumar. If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.

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