Write code to Checks if a string is an integer.
//package com.book2s; public class Main { public static void main(String[] argv) { String str = "book2s.com"; System.out.println(isInteger(str)); }/*from w w w. j a va2 s . co m*/ /** * Checks if is integer. * * @param str * the str * @return true, if is integer * @see <a href= * "http://stackoverflow.com/questions/237159/whats-the-best-way-to-check-to-see-if-a-string-represents-an-integer-in-java"> * Stackoverflow question on faster options to Integer.parseInt()</a> */ public static boolean isInteger(String str) { if (str.isEmpty()) return false; int length = str.length(), i = 0; if (str.charAt(0) == '-') { if (length == 1) { return false; } i = 1; } for (; i < length; i++) { char c = str.charAt(i); if (c < '0' || c > '9') { if (c != '-') { return false; } } } return true; } }