Get Next Monday : Date Calculation « Data Type « Java

1. Java
2. Data Type
3. Date Calculation

Get Next Monday

    
/*
    Copyright (C) 2008-2009 Dmitry Gusev <dmitry.gusev@gmail.com>

    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU 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 General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.

 */
 
 
import java.util.Calendar;
import java.util.Date;


public class Util {
    public static Date getMonday(Date today) {
        Calendar cal = Calendar.getInstance();
        
        cal.setTime(today);

        int dow = cal.get(Calendar.DAY_OF_WEEK);
        
        while (dow != Calendar.MONDAY) {
            int date = cal.get(Calendar.DATE);
            
            if (date == 1) {
                int month = cal.get(Calendar.MONTH);
                
                if (month == Calendar.JANUARY) {
                    month = Calendar.DECEMBER;
                    
                    cal.set(Calendar.YEAR, cal.get(Calendar.YEAR) - 1);
                } else {
                    month--;
                }
                
                cal.set(Calendar.MONTH, month);
                
                date = getMonthLastDate(month, cal.get(Calendar.YEAR));
            } else {
                date--;
            }
            
            cal.set(Calendar.DATE, date);
            
            dow = cal.get(Calendar.DAY_OF_WEEK);
        }
        
        return cal.getTime();
    }
    private static int getMonthLastDate(int month, int year) {
        switch (month) {
            case Calendar.JANUARY:  
            case Calendar.MARCH:
            case Calendar.MAY:
            case Calendar.JULY:
            case Calendar.AUGUST:
            case Calendar.OCTOBER:
            case Calendar.DECEMBER:
                return 31;

            case Calendar.APRIL:
            case Calendar.JUNE:
            case Calendar.SEPTEMBER:
            case Calendar.NOVEMBER:
                return 30;
                
            default:    //  Calendar.FEBRUARY
                return year % 4 == 0 ? 29 : 28;
        }
    }
}

   
    
    
    
  

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