DateValidator.java

/*
 * Created on 13-3-30
 * 
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
 * in compliance with the License. You may obtain a copy of the License at
 * 
 * http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software distributed under the License
 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
 * or implied. See the License for the specific language governing permissions and limitations under
 * the License.
 * 
 * Copyright @2013 the original author or authors.
 */
package ch13string.regex;

/**
 * Description of this file.
 *
 * @author XiongNeng
 * @version 1.0
 * @since 13-3-30
 */

import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class DateValidator {

    private Pattern pattern;
    private Matcher matcher;

    private static final String DATE_PATTERN = "(0?[1-9]|[12][0-9]|3[01])/(0?[1-9]|1[012])/((19|20)\\d\\d)";

    public DateValidator() {
        pattern = Pattern.compile(DATE_PATTERN);
    }

    /**
     * Validate date format with regular expression
     *
     * @param date date address for validation
     * @return true valid date fromat, false invalid date format
     */
    public boolean validate(final String date) {
        matcher = pattern.matcher(date);
        if (matcher.matches()) {
            matcher.reset();
            if (matcher.find()) {
                String day = matcher.group(1);
                String month = matcher.group(2);
                int year = Integer.parseInt(matcher.group(3));

                if (day.equals("31") &&
                        (month.equals("4") || month.equals("6") || month.equals("9") ||
                                month.equals("11") || month.equals("04") || month.equals("06") ||
                                month.equals("09"))) {
                    return false; // only 1,3,5,7,8,10,12 has 31 days
                } else if (month.equals("2") || month.equals("02")) {
                    //leap year
                    if (year % 4 == 0) {
                        return !(day.equals("30") || day.equals("31"));
                    } else {
                        return !(day.equals("29") || day.equals("30") || day.equals("31"));
                    }
                } else {
                    return true;
                }
            } else {
                return false;
            }
        } else {
            return false;
        }
    }
}