Get first/last date of current Week/Month

import java.util.Calendar;
import java.util.Date;

/**
 * Returns the date of previous Monday
 */
public static Date getFirstDateOfCurrentWeek() {
    Calendar cal = Calendar.getInstance();
    cal.set(Calendar.HOUR_OF_DAY, 0);
    cal.clear(Calendar.MINUTE);
    cal.clear(Calendar.SECOND);
    cal.clear(Calendar.MILLISECOND);
    cal.set(Calendar.DAY_OF_WEEK, Calendar.MONDAY);
    return cal.getTime();
}

/**
 * Returns the date of next Sunday.
 */
public static Date getLastDateOfCurrentWeek() {
    Calendar cal = Calendar.getInstance();
    cal.set(Calendar.HOUR_OF_DAY, 0);
    cal.clear(Calendar.MINUTE);
    cal.clear(Calendar.SECOND);
    cal.clear(Calendar.MILLISECOND);
    cal.set(Calendar.DAY_OF_WEEK, Calendar.MONDAY);

    Calendar last = (Calendar) cal.clone();
    last.add(Calendar.DAY_OF_YEAR, 7);
    last.add(Calendar.MILLISECOND, -1);
    return last.getTime();
}

/**
 * Get the first Date ( first millisecond ) of current month
 */
public static Date getFirstDateOfCurrentMonth() {
    Calendar cal = Calendar.getInstance();
    cal.set(Calendar.HOUR_OF_DAY, 0);
    cal.clear(Calendar.MINUTE);
    cal.clear(Calendar.SECOND);
    cal.clear(Calendar.MILLISECOND);
    cal.set(Calendar.DAY_OF_MONTH, 1);
    return cal.getTime();
}

/**
 * Get the last time ( last millisecond ) of current month
 */
public static Date getLastDateOfCurrentMonth() {
    Calendar cal = Calendar.getInstance();
    cal.set(Calendar.HOUR_OF_DAY, 0);
    cal.clear(Calendar.MINUTE);
    cal.clear(Calendar.SECOND);
    cal.clear(Calendar.MILLISECOND);
    cal.add(Calendar.MONTH, 1); // NEXT MONTH
    cal.set(Calendar.DAY_OF_MONTH, 1); // FIRST DAY OF NEXT MONTH
    cal.add(Calendar.MILLISECOND, -1); // Go one Millisecond back, which is the last moment of the last day of current month
    return cal.getTime();
}