Java Week Day getFirstDayOfWeek(String str, int week)

Description

get First Day Of Week

License

Open Source License

Declaration

public static String getFirstDayOfWeek(String str, int week) throws ParseException 

Method Source Code

//package com.java2s;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;

public class Main {

    public static String getFirstDayOfWeek(String str, int week) throws ParseException {
        String conStr = null;//from   w  ww.  ja va2  s  . c  o  m
        int dayOfWeek = 0;

        if (week == 0) {
            conStr = str;
            dayOfWeek = getCalendar(conStr).get(Calendar.DAY_OF_WEEK);
        } else {
            conStr = addDays(str, week * 7);
            dayOfWeek = getCalendar(conStr).get(Calendar.DAY_OF_WEEK);
        }

        int gap = 0;
        if (dayOfWeek != 1)
            gap = dayOfWeek - 2;
        else
            gap = 6;

        return addDays(conStr, -gap);
    }

    public static String getFirstDayOfWeek(Date date, int week) throws ParseException {
        Date conDate = null;
        int dayOfWeek = 0;

        if (week == 0) {
            conDate = date;
            dayOfWeek = getCalendar(conDate).get(Calendar.DAY_OF_WEEK);
        } else {
            conDate = addDays2Date(date, week * 7);
            dayOfWeek = getCalendar(conDate).get(Calendar.DAY_OF_WEEK);
        }

        int gap = 0;
        if (dayOfWeek != 1)
            gap = dayOfWeek - 2;
        else
            gap = 6;

        return addDays(conDate, -gap);
    }

    public static Calendar getCalendar(String str) {
        int yy = Integer.parseInt(str.substring(0, 4));
        int mm = Integer.parseInt(str.substring(4, 6)) - 1;
        int dd = Integer.parseInt(str.substring(6, 8));

        Calendar cal = Calendar.getInstance();
        cal.set(yy, mm, dd);
        return cal;
    }

    public static Calendar getCalendar(Date date) {
        Calendar cal = Calendar.getInstance();
        cal.setTime(date);
        return cal;
    }

    public static String addDays(String str, int days) throws ParseException {
        SimpleDateFormat fmt = new SimpleDateFormat("yyyyMMdd");
        Date date = fmt.parse(str);
        date.setTime(date.getTime() + (long) days * 1000L * 60L * 60L * 24L);
        return fmt.format(date);
    }

    public static String addDays(Date date, int days) throws ParseException {
        SimpleDateFormat fmt = new SimpleDateFormat("yyyyMMdd");
        date.setTime(date.getTime() + (long) days * 1000L * 60L * 60L * 24L);
        return fmt.format(date);
    }

    public static Date addDays2Date(String str, int days) throws ParseException {
        SimpleDateFormat fmt = new SimpleDateFormat("yyyyMMdd");
        Date date = fmt.parse(str);
        date.setTime(date.getTime() + (long) days * 1000L * 60L * 60L * 24L);
        return date;
    }

    public static Date addDays2Date(Date date, int days) throws ParseException {
        date.setTime(date.getTime() + (long) days * 1000L * 60L * 60L * 24L);
        return date;
    }
}

Related

1. getFirstDayOfWeek()
2. getFirstDayOfWeek(Date date)
3. getFirstDayOfWeek(Date date)
4. getFirstDayOfWeek(final Date date)
5. getFirstDayOfWeek(String format)
6. getFirstDayOfWeek(String week)
7. getFirstDayOfWeek(String week)
8. getFriday(Date date)
9. getLastDayOfCurrWeek()