DateUtil.java

/*
 * Copyright 2002-2007 the original author or authors.
 *
 * 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.
 */

package org.opentides.util;

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;
import java.util.GregorianCalendar;
import java.util.TimeZone;

public class DateUtil {
	
	/**
	 * Hide the constructor.
	 */
	private DateUtil() {		
	}
	
	public static String dateToString(Date obj, String format) {
    	if (obj == null)
    		return "";
        SimpleDateFormat dtFormatter = new SimpleDateFormat(format);
        return dtFormatter.format(obj);	
	}
    
    public static Date stringToDate(String strDate, String format) throws ParseException {
        if (StringUtil.isEmpty(strDate))
        	return null;
        SimpleDateFormat dtFormatter = new SimpleDateFormat(format);
       	return dtFormatter.parse(strDate.trim());
    }
    
    public static Date convertFlexibleDate(String strDate, String[] formats) throws ParseException {
    	if (StringUtil.isEmpty(strDate))
    		return null;    	
    	for (int i=0; i<formats.length; i++) {
            try {
            	SimpleDateFormat dtFormatter = new SimpleDateFormat(formats[i]);
            	dtFormatter.setLenient(false);
            	return dtFormatter.parse(strDate.trim());
            } catch (ParseException e) {
            	// do nothing... try other format
            }    	
    	}
    	// we are unable to convert
    	throw new ParseException("No matching date format for "+strDate, 0);    	
    }

    public static String convertShortDate(Date obj) {
    	return dateToString(obj, "yyyyMMdd");
    }
    
    public static Date convertShortDate(String str) throws ParseException {
    	return stringToDate(str, "yyyyMMdd");
    }

    public static Date convertShortDate(String str, Date defaultDate) throws ParseException {
   		return stringToDate(str, "yyyyMMdd");
    }
 
    public static Date convertFlexibleDate(String strDate) throws ParseException {
    	String[] formats = { "MM/dd/yyyy",
    					     "MM-dd-yyyy", 
    					     "yyyyMMdd",
    					     "yyyy-MM-dd",
						     "MMM dd yyyy",
						     "MMM dd, yyyy",
    					     "MMM yyyy",
						     "MM/yyyy",
						     "MM-yyyy",
						     "yyyy"};

   		return convertFlexibleDate(strDate, formats);
    }   
    
    public static boolean compareNullableDates(Date date1, Date date2) {
    	if ((date1==null) && (date2==null))
    		return true;
    	if (date1!=null) {
    		if (date1.equals(date2))
    			return true;
    		else
    			return false;
    	}
    	return false;
    }
    
    /**
     * Checks if the given date has a time recorded or just plain 00:00:00.000
     * @param date
     * @return
     */
	public static boolean hasTime(Date date) {
    	if (date == null)
    		return false;
    	Calendar cal = Calendar.getInstance();
    	cal.setTime(date);
    	return (cal.get(Calendar.HOUR_OF_DAY) + cal.get(Calendar.MINUTE) + cal.get(Calendar.SECOND) + cal.get(Calendar.MILLISECOND) > 0);
    }
    
    /**
	 * Get current date according to client's time zone.
	 * @param calendar - adapting calendar
	 * @param timeZone - client time zone
	 * @return adapt calendar to client time zone
	 */
	public static Date getClientCurrentDate(final Calendar calendar, final TimeZone timeZone) {
	    Calendar result = new GregorianCalendar(timeZone);
	    result.setTimeInMillis(calendar.getTimeInMillis() +
	            timeZone.getOffset(calendar.getTimeInMillis()) -
	            TimeZone.getDefault().getOffset(calendar.getTimeInMillis()));
	    result.getTime();
	    return result.getTime();
	}
	
	/**
	 * Computes for days ago or ahead given the date and the count. Set to negative if operation will
	 * be computing for a past date
	 * @param count
	 * @param date
	 * @return
	 */
	public static Date getDateFrom(int count, Date date){
		
		Calendar calendar = Calendar.getInstance();
		calendar.setTime(date);
		
		calendar.add(Calendar.DAY_OF_MONTH, count);
		return calendar.getTime();
	}
	
	/**
	 * returns the specified day of the week given the week number and year
	 * @param day: 0 = sun, 1 = mon, 2 = tue, 3 = wed, 4 = thur, 5 = fri, 6 = sat
	 * @param week
	 * @param year
	 * @return
	 */
	public static Date getDayOfTheWeek(int day, int week, int year){
		Calendar calendar = Calendar.getInstance();
		calendar.clear();
		calendar.set(Calendar.WEEK_OF_YEAR, week);
		calendar.set(Calendar.YEAR, year);
		calendar.add(Calendar.DATE, day);
		
		return calendar.getTime();
	}
	
	/**
	 * Remove time field from the date
	 * @param date
	 * @return
	 */
	public static Date removeTime(Date date) {
		Calendar cal = Calendar.getInstance();
		cal.setTime(date);
		cal.set(Calendar.HOUR_OF_DAY, 0);
		cal.set(Calendar.MINUTE, 0);
		cal.set(Calendar.SECOND, 0);
		cal.set(Calendar.MILLISECOND, 0);
		return cal.getTime();
	}
}