Format double value in scientific notation

Question

I have a double number like 223.45654543434 and I need to show it like "0.223x10E-3".

How can I do this in Java?

Answer 1

From http://www.java-tips.org/java-se-tips/java.text/display-numbers-in-scientific-notation.html

Copy/pasting because the page seems to be having issues

=================

You can display numbers in scientific notation using java.text package. Specifically DecimalFormat class in java.text package can be used for this aim.

The following example shows how to do this:

import java.text.*;
import java.math.*;

public class TestScientific {

  public static void main(String args[]) {
     new TestScientific().doit();
  }

  public void doit() {
     NumberFormat formatter = new DecimalFormat();

     int maxinteger = Integer.MAX_VALUE;
     System.out.println(maxinteger);    // 2147483647

     formatter = new DecimalFormat("0.######E0");
     System.out.println(formatter.format(maxinteger)); // 2,147484E9

     formatter = new DecimalFormat("0.#####E0");
     System.out.println(formatter.format(maxinteger)); // 2.14748E9


     int mininteger = Integer.MIN_VALUE;
     System.out.println(mininteger);    // -2147483648

     formatter = new DecimalFormat("0.######E0");
     System.out.println(formatter.format(mininteger)); // -2.147484E9

     formatter = new DecimalFormat("0.#####E0");
     System.out.println(formatter.format(mininteger)); // -2.14748E9

     double d = 0.12345;
     formatter = new DecimalFormat("0.#####E0");
     System.out.println(formatter.format(d)); // 1.2345E-1

     formatter = new DecimalFormat("000000E0");
     System.out.println(formatter.format(d)); // 12345E-6
  }
}  

Answer 2

    System.out.println(String.format("%6.3e",223.45654543434));

results in

    2.235e+02

which is the closest I get.

more info : http://java.sun.com/j2se/1.5.0/docs/api/java/util/Formatter.html#syntax

Answer 3

Finally I do it by hand:

public static String parseToCientificNotation(double valor) {
        int cont = 0;
        java.text.DecimalFormat DECIMAL_FORMATER = new java.text.DecimalFormat("0.##");
        while (((int) valor) != 0) {
            valor /= 10;
            cont++;
        }
        return DECIMAL_FORMATER.format(valor).replace(",", ".") + " x10^ -" + cont;
}

thanks to all :)