Here you can find the source of isInteger(String s)
public static boolean isInteger(String s)
//package com.java2s; /* /*from w ww . j ava2 s . c o m*/ * The MIT License * ================================================================================== * Copyright 2016 SIPHYC SYSTEMS Sdn Bhd All Rights Reserved. * * project reference code contributed by Moaz Korena <korena@siphyc.com,moazkorena@gmail.com> * * Permission is hereby granted, free of charge, to any person obtaining a copy * of this software and associated documentation files (the "Software"), to deal * in the Software without restriction, including without limitation the rights * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell * copies of the Software, and to permit persons to whom the Software is * furnished to do so, subject to the following conditions: * * The above copyright notice and this permission notice shall be included in * all copies or substantial portions of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN * THE SOFTWARE. */ import java.util.Scanner; public class Main { public static boolean isInteger(String s) { return isInteger(s, 10); } public static boolean isInteger(String s, int radix) { Scanner sc = new Scanner(s.trim()); if (!sc.hasNextInt(radix)) { return false; } // we know it starts with a valid int, now make sure // there's nothing left! sc.nextInt(radix); return !sc.hasNext(); } }