Java tutorial
/* Copyright 2015 CrushPaper.com. This file is part of CrushPaper. CrushPaper is free software: you can redistribute it and/or modify it under the terms of version 3 of the GNU Affero General Public License as published by the Free Software Foundation. CrushPaper 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 CrushPaper. If not, see <http://www.gnu.org/licenses/>. */ package com.crushpaper; import java.util.regex.Pattern; import org.apache.commons.lang3.StringUtils; /** Contains helper methods for validating fields in the account. */ public class AccountAttributeValidator { /** Returns true if the username is valid. */ static boolean isUserNameValid(String value) { return value != null && value.length() >= 3 && value.length() <= 20 && Pattern.compile("^[a-z0-9]+$").matcher(value).find(); } /** Returns true if the password is valid. */ public static boolean isPasswordValid(String value) { return value != null && value.length() >= 8 && value.length() <= 20 && StringUtils.isAsciiPrintable(value); } /** Returns true if the email is valid. */ public static boolean isEmailValid(String value) { return value != null && value.length() <= 100 && Pattern .compile("^[a-zA-Z0-9!#$%&'*+-/=?^_`{|}~.]+@[a-zA-Z0-9-.]+\\.[a-zA-Z0-9]+$").matcher(value).find(); } }