How to handle NumberFormatException

//Sample program to handle Number Format Exception.

package com.gaurav.java.others;

public class NumberFormatExceptiontest {

 private static String number = "140.56";
 private static String testStr = "GAURAV";

 private static Double getTransactionAmount(String number) {
                      Double xx = Double.parseDouble(number);
                      return xx;
                 }

public static boolean isNum(String s) {
                try {
                        Double.parseDouble(s);
                     } catch (NumberFormatException nfe) {
                return false;
            }
          return true;
        }

 public static void main(String args[]) {

  // Check for number.

  boolean flag = isNum(number);
  Double num = 0.0;

  System.out.println("flag--" + flag);

             if (flag) {
                            num = getTransactionAmount(number);
                       }
  System.out.println("Number is-" + num);

  // Check for actual String value.

                    boolean flag1 = isNum(testStr);
                    Double num1 = 0.0;
                    System.out.println("flag1 value --" + flag1);

           if (flag1) {
                             num1 = getTransactionAmount(testStr);
                         }
                     System.out.println("Number is-" + num1);
                    }
               }