Java Day of Week getDayofWeekForContainedDate(Date dt, DayOfWeek dow)

Description

Find the day of week within the week that the dt is part of.

License

Open Source License

Parameter

Parameter	Description
dt	a parameter
dow	a parameter

Exception

Parameter	Description
Exception	an exception

Declaration

public static Date getDayofWeekForContainedDate(Date dt, DayOfWeek dow) throws Exception 

Method Source Code

//package com.java2s;
//License from project: Open Source License 

import java.time.*;

import java.time.temporal.TemporalAdjusters;
import java.util.Date;

public class Main {
    /**/*from w  w w.  j  a va  2s. c o  m*/
     * Find the day of week within the week that the dt is part of.
     *
     * @param dt
     * @param dow
     * @return
     * @throws Exception
     */
    public static Date getDayofWeekForContainedDate(Date dt, DayOfWeek dow) throws Exception {
        LocalDate dtLocalDate = dateToSystemLocalDate(dt);
        LocalDateTime dtLocalDateTime = dtLocalDate.atStartOfDay();
        dtLocalDate = dtLocalDateTime.toLocalDate();
        Date retDate;
        if (isDayOfWeek(dtLocalDate, dow)) {
            retDate = localDateToSystemAdjustedStartOfDayDate(dtLocalDate);
        } else {
            int dtVal = dtLocalDateTime.getDayOfWeek().getValue();
            int dowVal = dow.getValue();

            LocalDate tempLocalDate;
            if (dowVal > dtVal) {
                tempLocalDate = dtLocalDate.with(TemporalAdjusters.next(dow));
            } else {
                tempLocalDate = dtLocalDate.with(TemporalAdjusters.previous(dow));
            }
            retDate = localDateToSystemAdjustedStartOfDayDate(tempLocalDate);
        }
        return retDate;
    }

    /**
     * Takes a java.util.Date and turns it into a LocalDate based on the
     * systems default timezone.
     *
     * @param d
     * @return
     * @throws Exception
     */
    public static LocalDate dateToSystemLocalDate(Date d) throws Exception {
        return d.toInstant().atZone(ZoneId.systemDefault()).toLocalDate();
    }

    /**
     * Check the LocalDate given to see if it is the DayOfWeek given
     *
     * @param d
     * @param dow
     */
    public static boolean isDayOfWeek(LocalDate d, DayOfWeek dow) throws Exception {
        if (d.getDayOfWeek().compareTo(dow) == 0) {
            return true;
        } else {
            return false;
        }
    }

    /**
     * Adjusts a LocalDate to Midnight of the say day (start of day).
     *
     * @param d
     * @return
     * @throws Exception
     */
    public static Date localDateToSystemAdjustedStartOfDayDate(LocalDate d) throws Exception {
        LocalDateTime ldt = d.atStartOfDay();
        return getSystemDefaultDate(ldt);
    }

    /**
     * Get local system Date from LocalDateTime
     *
     * @param ldt
     * @return
     * @throws Exception
     */
    public static Date getSystemDefaultDate(LocalDateTime ldt) throws Exception {
        return Date.from(ldt.atZone(ZoneId.systemDefault()).toInstant());
    }
}

Related

1. getDayOfWeek(String datetime)
2. getDayOfWeek(String f)
3. getDayOfWeek(String format, int calendarField)
4. getDayOfWeekAsString(String sYear, String sMonth, String sDay)
5. getDayofWeekByDay(String year, String month, String day)
6. getDaysByWeek(Integer month, Integer year, Integer week)
7. getDaysByWeek2(Integer month, Integer year, Integer begin)
8. getDayWeekDate(String dateStr)
9. getDayWeekDateStr(Date date)