Given the date from the specified GregorianCalendar instance, returns the date of monday in the same week. - Java java.util

Java examples for java.util:Week

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Description

Given the date from the specified GregorianCalendar instance, returns the date of monday in the same week.

Demo Code

/**//w w w. j a va 2  s  . c  om
 * Copyright (c) 2010 Martin Geisse
 *
 * This file is distributed under the terms of the MIT license.
 */
import java.util.Calendar;
import java.util.Date;
import java.util.GregorianCalendar;

public class Main{
    /**
     * Given the date from the specified {@link GregorianCalendar} instance, returns
     * the date of monday in the same week. Monday is considered the first day of week
     * by this method. Note that the returned day may be in the previous month and even
     * year.
     * 
     * The time part of the returned object is unspecified.
     * @param anchorDate the date to start from
     * @return the date of monday in the same week
     */
    public static GregorianCalendar getMondayFromDate(
            GregorianCalendar anchorDate) {
        int dayOfMonth = anchorDate.get(Calendar.DAY_OF_MONTH);
        Month month = Month.from(anchorDate);
        int year = anchorDate.get(Calendar.YEAR);
        return getMondayFromDate(year, month, dayOfMonth);
    }
    /**
     * Given the specified year, month and day of month, returns the date of monday
     * in the same week. Monday is considered the first day of week by this method.
     * Note that the returned day may be in the previous month and even year.
     * 
     * The time part of the returned object is unspecified.
     * 
     * @param year the year to start from
     * @param month the month to start from
     * @param dayOfMonth the day of month to start from
     * @return the date of monday in the same week
     */
    public static GregorianCalendar getMondayFromDate(int year,
            Month month, int dayOfMonth) {
        GregorianCalendar c = new GregorianCalendar();
        setTimeToMidnight(c);
        c.set(Calendar.YEAR, year);
        c.set(Calendar.MONTH, month.getGregorianCalendarValue());
        c.set(Calendar.DAY_OF_MONTH, dayOfMonth);
        DayOfWeek argumentDayOfWeek = DayOfWeek.from(c);
        c.add(Calendar.DAY_OF_MONTH,
                -(argumentDayOfWeek.ordinal() - DayOfWeek.MONDAY.ordinal()));
        return c;
    }
    /**
     * Sets the time fields (24-hour, minute, second, millisecond) of the specified
     * {@link GregorianCalendar} instance to 0 so it subsequently represents midnight
     * of the same day as before.
     * @param c the instance to modify
     */
    public static void setTimeToMidnight(GregorianCalendar c) {
        c.set(Calendar.HOUR_OF_DAY, 0);
        c.set(Calendar.MINUTE, 0);
        c.set(Calendar.SECOND, 0);
        c.set(Calendar.MILLISECOND, 0);
    }
}

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