public static String toScientific(double num,int places) { 
   double power=(int)(Math.log(num)/Math.log(10));
   if(power < 0) power--;
   double fraction=num/Math.pow(10,power);
   String result="";     
   String sign="";
   fraction=round(fraction,places); 
   if(power > 0) sign="+";
   result+=fraction+"e"+sign+power;
   return result;
   }
   
public static double round(double value, int decimalPlace) {
   double power_of_ten = 1;
   while (decimalPlace-- > 0)
      power_of_ten *= 10.0;
   return Math.round(value * power_of_ten) / power_of_ten;
   }
   

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
  }
}