Java Parse Date parseDate(String dateString)

Description

parse Date

License

Apache License

Declaration

public static Date parseDate(String dateString) throws ParseException 

Method Source Code

//package com.java2s;
//License from project: Apache License 

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.HashMap;
import java.util.Map;

public class Main {
    private static final Map<String, String> DATE_FORMAT_REGEXPS = new HashMap<String, String>() {
        private static final long serialVersionUID = 1L;
        {/*from ww w  .  ja  v  a 2 s . c  om*/
            put("^\\d{8}$", "yyyyMMdd");
            put("^\\d{1,2}-\\d{1,2}-\\d{4}$", "dd-MM-yyyy");
            put("^\\d{4}-\\d{1,2}-\\d{1,2}$", "yyyy-MM-dd");
            put("^\\d{1,2}/\\d{1,2}/\\d{4}$", "MM/dd/yyyy");
            put("^\\d{4}/\\d{1,2}/\\d{1,2}$", "yyyy/MM/dd");
            put("^\\d{1,2}\\s[a-z]{3}\\s\\d{4}$", "dd MMM yyyy");
            put("^\\d{1,2}\\s[a-z]{4,}\\s\\d{4}$", "dd MMMM yyyy");
            put("^\\d{12}$", "yyyyMMddHHmm");
            put("^\\d{8}\\s\\d{4}$", "yyyyMMdd HHmm");
            put("^\\d{1,2}-\\d{1,2}-\\d{4}\\s\\d{1,2}:\\d{2}$", "dd-MM-yyyy HH:mm");
            put("^\\d{4}-\\d{1,2}-\\d{1,2}\\s\\d{1,2}:\\d{2}$", "yyyy-MM-dd HH:mm");
            put("^\\d{1,2}/\\d{1,2}/\\d{4}\\s\\d{1,2}:\\d{2}$", "MM/dd/yyyy HH:mm");
            put("^\\d{4}/\\d{1,2}/\\d{1,2}\\s\\d{1,2}:\\d{2}$", "yyyy/MM/dd HH:mm");
            put("^\\d{1,2}\\s[a-z]{3}\\s\\d{4}\\s\\d{1,2}:\\d{2}$", "dd MMM yyyy HH:mm");
            put("^\\d{1,2}\\s[a-z]{4,}\\s\\d{4}\\s\\d{1,2}:\\d{2}$", "dd MMMM yyyy HH:mm");
            put("^\\d{14}$", "yyyyMMddHHmmss");
            put("^\\d{8}\\s\\d{6}$", "yyyyMMdd HHmmss");
            put("^\\d{1,2}-\\d{1,2}-\\d{4}\\s\\d{1,2}:\\d{2}:\\d{2}$", "dd-MM-yyyy HH:mm:ss");
            put("^\\d{4}-\\d{1,2}-\\d{1,2}\\s\\d{1,2}:\\d{2}:\\d{2}$", "yyyy-MM-dd HH:mm:ss");
            put("^\\d{1,2}/\\d{1,2}/\\d{4}\\s\\d{1,2}:\\d{2}:\\d{2}$", "MM/dd/yyyy HH:mm:ss");
            put("^\\d{4}/\\d{1,2}/\\d{1,2}\\s\\d{1,2}:\\d{2}:\\d{2}$", "yyyy/MM/dd HH:mm:ss");
            put("^\\d{1,2}\\s[a-z]{3}\\s\\d{4}\\s\\d{1,2}:\\d{2}:\\d{2}$", "dd MMM yyyy HH:mm:ss");
            put("^\\d{1,2}\\s[a-z]{4,}\\s\\d{4}\\s\\d{1,2}:\\d{2}:\\d{2}$", "dd MMMM yyyy HH:mm:ss");
        }
    };

    public static Date parseDate(String dateString) throws ParseException {
        String dateFormat = determineDateFormat(dateString);
        if (dateFormat == null) {
            return null;
        }
        SimpleDateFormat df = new SimpleDateFormat(dateFormat);
        return df.parse(dateString);
    }

    /**
     * Determine SimpleDateFormat pattern matching with the given date string. Returns null if
     * format is unknown. You can simply extend DateUtil with more formats if needed.
     * @param dateString The date string to determine the SimpleDateFormat pattern for.
     * @return The matching SimpleDateFormat pattern, or null if format is unknown.
     * @see SimpleDateFormat
     */
    public static String determineDateFormat(String dateString) {
        for (String regexp : DATE_FORMAT_REGEXPS.keySet()) {
            if (dateString.toLowerCase().matches(regexp)) {
                return DATE_FORMAT_REGEXPS.get(regexp);
            }
        }
        return null; // Unknown format.
    }
}

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