Write code to Check whether the given string represents a number.
/* * Copyright (c) 2001-2002, Marco Hunsicker. All rights reserved. * * This software is distributable under the BSD license. See the terms of the * BSD license in the documentation provided with this software. */// www .j a v a 2s. co m //package com.book2s; public class Main { public static void main(String[] argv) { String str = "book2s.com"; System.out.println(isNumber(str)); } /** * Checks whether the given string represents a number. * * @param str string to check. * * @return <code>true</code> if <em>str</em> represents a number. */ public static boolean isNumber(String str) { if (str == null) { return false; } int letters = 0; for (int i = 0, size = str.length(); i < size; i++) { if ((str.charAt(i) < 48) || (str.charAt(i) > 57)) { letters++; } } if ((letters > 1) || ((letters == 1) && (str.length() == 1))) { return false; } return true; } }