Here you can find the source of isNumeric(String str)
public static boolean isNumeric(String str)
//package com.java2s; /*############################################################################## Copyright (C) 2011 HPCC Systems.// ww w.j a v a 2 s .c om All rights reserved. This program is free software: you can redistribute it and/or modify it under the terms of the GNU Affero General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License for more details. You should have received a copy of the GNU Affero General Public License along with this program. If not, see <http://www.gnu.org/licenses/>. ############################################################################## */ import java.text.NumberFormat; import java.util.Locale; public class Main { public static final ThreadLocal<NumberFormat> NUMFORMATTER = new ThreadLocal<NumberFormat>() { @Override protected NumberFormat initialValue() { return NumberFormat.getInstance(Locale.US); } }; public static boolean isNumeric(String str) { try { NUMFORMATTER.get().parse(str); } catch (Exception e) { return false; } return true; } }