String Utility

/*This program Demonstrates the proper use of Number Formats in common java programming scenarios */

import java.math.BigDecimal;
import java.text.DecimalFormat;
import java.text.DecimalFormatSymbols;
import java.util.Locale;

/**
* Class provides common functions on number formats.
*/

public class NumberUtility {
 
   /**
    * Method takes Object as parameter and returns decimal number.
    * if argument is float or double and contains tailing zeros
    * it removes them. If argument is float or double then no change in return type.
    * Change the Format of the Number by changing the String Pattern
    */
   public static String changeToDecimalFormat(Object number) {

       BigDecimal bdNumber = new BigDecimal(number.toString());
       bdNumber = bdNumber.stripTrailingZeros();           //Returns a BigDecimal with any trailing zero's removed
       String pattern = "###,##0.0###########";  //To apply formatting when the number of digits in input equals the pattern
       DecimalFormat newFormat = new DecimalFormat(pattern, new DecimalFormatSymbols(Locale.US));
       return newFormat.format(bdNumber);

   }

   /* Method takes Object as parameter and removes commas from the parameter */
   public static double removeCommasFromNumber(Object number) {
       try {
           StringBuffer inputNo = new StringBuffer(number.toString());
           if (inputNo.length() > 0) {
               while (inputNo.indexOf(",") != -1) {
                   inputNo.deleteCharAt(inputNo.indexOf(","));
               }
           } else {
               return 0.0;
           }
           return Double.parseDouble(inputNo.toString());

       } catch (NumberFormatException e) {
           return 0.0;
       }
   }

   /* Some times its required to have a fixed set of decimal places for a
    * number. We can set that by changing the precision number for a particular
    * input BigDecimal Input String
    */
   public static String changeToRequiredDecimals(String bigDecimalString,
           int precision) {
       String newFormattedString = null;
       String afterDecimal = null;
       if (bigDecimalString == null || bigDecimalString.length() == 0) {
           return "0.0";
       }
       if (bigDecimalString.contains(".")) {
           afterDecimal = bigDecimalString.substring(bigDecimalString
                   .indexOf(".") + 1);
           int length = Math.abs((afterDecimal.length() - precision));
           if (afterDecimal.length() < precision) {
               newFormattedString = bigDecimalString;
               for (int i = 0; i < length; i++) {
                   newFormattedString = newFormattedString + "0";
               }
           } else if (afterDecimal.length() > precision) {
               newFormattedString = bigDecimalString.substring(0,
                       bigDecimalString.length() - length);
               if (precision == 0) {
                   newFormattedString = newFormattedString.substring(0,
                           newFormattedString.indexOf("."));
             } else {
                 newFormattedString = bigDecimalString;
             }

         } else {
              if (precision > 0)
                  newFormattedString = bigDecimalString + ".";
              else
                  newFormattedString = bigDecimalString;
              for (int i = 0; i < precision; i++) {
                  newFormattedString = newFormattedString + "0";
              }
         }
       }
       return newFormattedString;
   }

   public static void main(String args[]){
    int intVar = 10;
    double doubleVar = 10.504000;
    float floatVar = 343534534348.5687654F;
    String commaString = "343,534,535,000.0";
    BigDecimal bdNumber = new BigDecimal("1234.8765");
    
    
    System.out.println(NumberUtility.changeToDecimalFormat(new Integer(intVar)));
    System.out.println(NumberUtility.changeToDecimalFormat(new Double(doubleVar)));
    System.out.println(NumberUtility.changeToDecimalFormat(new Float(floatVar)));
    
    System.out.println(NumberUtility.removeCommasFromNumber(commaString));
    
    System.out.println(NumberUtility.changeToRequiredDecimals(bdNumber.toString(), 8));
 
   }
}