Useful java class: GetStartFinishDateTimeOfWeekOfDay

package custom;
import java.util.Date;
import java.util.Locale;

import com.ibm.icu.util.Calendar;

public class GetStartFinishDateTimeOfWeekOfDay {

  public static Date GetStartDateTimeOfDay(Date reportDate) {

   Calendar cal = Calendar.getInstance(new Locale("ru", "UA"));
   cal.setTime(reportDate);
   cal.set(Calendar.MILLISECONDS_IN_DAY, 0);
   reportDate = cal.getTime();

   return reportDate;

  }

  public static Date GetFinishDateTimeOfDay(Date reportDate) {

   Calendar cal = Calendar.getInstance(new Locale("ru", "UA"));
   cal.setTime(reportDate);
   cal.set(Calendar.MILLISECONDS_IN_DAY, 86399999);
   reportDate = cal.getTime();

   return reportDate;

  }

  public static Date GetStartDateTimeOfWeek(Date reportDate) {

   Calendar cal = Calendar.getInstance(new Locale("ru", "UA"));
   cal.setTime(reportDate);
   cal.setFirstDayOfWeek(Calendar.MONDAY);
   cal.set(Calendar.DAY_OF_WEEK, Calendar.MONDAY);
   cal.set(Calendar.MILLISECONDS_IN_DAY, 0);
   Date startWeekDate = cal.getTime();

   return startWeekDate;

  }

  // last day is Sunday
  public static Date GetFinishDateTimeOfWeek(Date reportDate) {

   Calendar cal = Calendar.getInstance(new Locale("ru", "UA"));
   cal.setTime(reportDate);
   cal.setFirstDayOfWeek(Calendar.MONDAY);
   cal.set(Calendar.DAY_OF_WEEK, Calendar.SUNDAY);
   cal.set(Calendar.MILLISECONDS_IN_DAY, 86399999);
   Date finishWeekDate = cal.getTime();

   return finishWeekDate;

  }

  // last day is Friday
  public static Date GetFinishDateTimeOfWeek_Work(Date reportDate) {

   Calendar cal = Calendar.getInstance(new Locale("ru", "UA"));
   cal.setTime(reportDate);
   cal.setFirstDayOfWeek(Calendar.MONDAY);
   cal.set(Calendar.DAY_OF_WEEK, Calendar.FRIDAY);
   cal.set(Calendar.MILLISECONDS_IN_DAY, 86399999);
   Date finishWeekDate = cal.getTime();

   return finishWeekDate;

  }

}