Java implements the input of a time period and the corresponding number of weeks to obtain the date of these weeks in this time period

Java implements the input of a time period and the corresponding number of weeks to obtain the date of these weeks in this time period

Recently, I have encountered a problem. For a given period of time and a specific week, I need to obtain all the days of the given week in this period of time.

For example, get the dates of all Monday and Tuesday from.

Package com. cc. common;


Import java. text. ParseException;
Import java. text. SimpleDateFormat;
Import java. util .*;




Public class WeekDayUtil {


/**
* Enter a date period and the corresponding number of weeks to obtain the date of these weeks.
*/
Private static Map WeekNumberMap = new HashMap ();
Static {
WeekNumberMap. put (0, 1 );
WeekNumberMap. put (1, 2 );
WeekNumberMap. put (2, 3 );
WeekNumberMap. put (3, 4 );
WeekNumberMap. put (4, 5 );
WeekNumberMap. put (5, 6 );
WeekNumberMap. put (6, 7 );


}


Public static List GetDates (String dateFrom, String dateEnd, List WeekDays ){
Long time;
Long perDayMilSec = 24L * 60*60*1000;
List DateList = new ArrayList ();
SimpleDateFormat sdf = new SimpleDateFormat ("yyyy-MM-dd ");
// Week coefficient to be queried
String strWeekNumber = weekForNum (weekDays );
Try {
DateFrom = sdf. format (sdf. parse (dateFrom). getTime ()-perDayMilSec );
While (true ){
Time = sdf. parse (dateFrom). getTime ();
Time = time + perDayMilSec;
Date date = new Date (time );
DateFrom = sdf. format (date );
If (dateFrom. compareTo (dateEnd) <= 0 ){
// Week coefficient of a certain time point of query
Integer weekDay = dayForWeek (date );
// Determine whether the week coefficient of the current date needs to be queried
If (strWeekNumber. contains (weekDay. toString ())){
DateList. add (dateFrom );
}
} Else {
Break;
}
}
} Catch (ParseException e ){
E. printStackTrace ();
}
Return dateList;
}


// Wait until the week coefficient of the current time. Sunday: 1, Monday: 2, Tuesday: 3, Wednesday: 4, Thursday: 5, Friday: 6, Saturday: 7
Public static Integer dayForWeek (Date date ){
Calendar calendar = Calendar. getInstance ();
Calendar. setTime (date );
Return calendar. get (Calendar. DAY_OF_WEEK );
}


/**
* Obtain the ratio of the week.
*/
Public static String weekForNum (List WeekDays ){
// The returned result is the weekly coefficient of the combination.
String weekNumber = "";


For (Integer weekDay: weekDays ){
WeekNumber = weekNumber + "" + getWeekNum (weekDay). toString ();
}
Return weekNumber;


}


// Convert the week to the corresponding coefficient 0, Sunday; 1, Monday; 2 ....
Public static Integer getWeekNum (int strWeek ){
Return weekNumberMap. get (strWeek );
}


Public static void main (String [] args ){
// Output the dates of all Monday and Tuesday from.
List DaysOfOneWeek = new ArrayList ();
DaysOfOneWeek. add (1 );
DaysOfOneWeek. add (2 );
List DaysNeedBookList = getDates ("2015-01-01", "2015-01-21", daysOfOneWeek );
For (String s: daysNeedBookList ){
System. out. println (s );
}
}
}

 

After the main method is tested, the output is:

2015-01-05
2015-01-06
2015-01-12
2015-01-13
2015-01-19
Septem