FormatFloatInJava.java

import java.text.DecimalFormat;
import java.util.Arrays;
import java.util.Formatter;
 
/**
* Java program to format float or double to String in Java. In this Java
* example, you will learn how to display a floating point number up-to 2 or 3
* decimal places.
*
* @author Javin Paul
*/
public class FormatFloatInJava {
 
    public static void main(String args[]) {
 
        // First task - format a floating point number up-to 2 decimal places
        float pi = 3.1428733f;
 
        // From Java 5, String has a format() method
        String str = String.format("%.02f", pi);
        System.out.println("formatted float up to 2 decimals " + str);
 
        // If you just want to display, you can combine above two 
        // by using printf()
        // syntax of formatting will remain same
        // this will display floating point number up-to 3 decimals
        System.out.printf("floating point number up-to 3 decimals : %.03f %n",
                               pi);
 
        // Alternatively you can also use Formatter class to 
        // format floating point numbers
        // Allocate a Formatter on the StringBuilder
        StringBuilder sb = new StringBuilder();
        Formatter formatter = new Formatter(sb);  
         // Send all outputs to StringBuilder
 
        // format() has the same syntax as printf()
        formatter.format("%.4f", pi);     // 4 decimal places
        System.out.println("Value of PI up to four decimals : " 
                   + formatter.toString());
        formatter.close();
 
        // Similarly you can format double to String in Java
        double price = 20.25;
        System.out.printf("Value of double up-to 2 decimals : %.2f", price);
 
       // best way to format floating point numbers in Java
       // beware it also round the numbers
      DecimalFormat df = new DecimalFormat("#.##");
      String formatted = df.format(2.456345); 
      System.out.println(formatted);  //prints 2.46

    }
 
}