Commons Lang、DateUtils.iterator()

everyday Java 
import java.util.*;
import org.apache.commons.lang.time.DateUtils;

public class C2009012400 {
    public static void main(String[] args) {
        GregorianCalendar c = new GregorianCalendar();
        Iterator iter = DateUtils.iterator(c, DateUtils.RANGE_WEEK_SUNDAY);

        while (iter.hasNext()) {
            System.out.println((GregorianCalendar)iter.next());
        }
    }
}

で、

java.util.GregorianCalendar[time=1232809200000,areFieldsSet=true,areAllFieldsSet=true,lenient=true,zone=sun.util.calendar.ZoneInfo[id="Asia/Tokyo",offset=32400000,dstSavings=0,useDaylight=false,transitions=10,lastRule=null],firstDayOfWeek=1,minimalDaysInFirstWeek=1,ERA=1,YEAR=2009,MONTH=0,WEEK_OF_YEAR=5,WEEK_OF_MONTH=5,DAY_OF_MONTH=25,DAY_OF_YEAR=25,DAY_OF_WEEK=1,DAY_OF_WEEK_IN_MONTH=4,AM_PM=0,HOUR=0,HOUR_OF_DAY=0,MINUTE=0,SECOND=0,MILLISECOND=0,ZONE_OFFSET=32400000,DST_OFFSET=0]
java.util.GregorianCalendar[time=1232895600000,areFieldsSet=true,areAllFieldsSet=true,lenient=true,zone=sun.util.calendar.ZoneInfo[id="Asia/Tokyo",offset=32400000,dstSavings=0,useDaylight=false,transitions=10,lastRule=null],firstDayOfWeek=1,minimalDaysInFirstWeek=1,ERA=1,YEAR=2009,MONTH=0,WEEK_OF_YEAR=5,WEEK_OF_MONTH=5,DAY_OF_MONTH=26,DAY_OF_YEAR=26,DAY_OF_WEEK=2,DAY_OF_WEEK_IN_MONTH=4,AM_PM=0,HOUR=0,HOUR_OF_DAY=0,MINUTE=0,SECOND=0,MILLISECOND=0,ZONE_OFFSET=32400000,DST_OFFSET=0]
java.util.GregorianCalendar[time=1232982000000,areFieldsSet=true,areAllFieldsSet=true,lenient=true,zone=sun.util.calendar.ZoneInfo[id="Asia/Tokyo",offset=32400000,dstSavings=0,useDaylight=false,transitions=10,lastRule=null],firstDayOfWeek=1,minimalDaysInFirstWeek=1,ERA=1,YEAR=2009,MONTH=0,WEEK_OF_YEAR=5,WEEK_OF_MONTH=5,DAY_OF_MONTH=27,DAY_OF_YEAR=27,DAY_OF_WEEK=3,DAY_OF_WEEK_IN_MONTH=4,AM_PM=0,HOUR=0,HOUR_OF_DAY=0,MINUTE=0,SECOND=0,MILLISECOND=0,ZONE_OFFSET=32400000,DST_OFFSET=0]
java.util.GregorianCalendar[time=1233068400000,areFieldsSet=true,areAllFieldsSet=true,lenient=true,zone=sun.util.calendar.ZoneInfo[id="Asia/Tokyo",offset=32400000,dstSavings=0,useDaylight=false,transitions=10,lastRule=null],firstDayOfWeek=1,minimalDaysInFirstWeek=1,ERA=1,YEAR=2009,MONTH=0,WEEK_OF_YEAR=5,WEEK_OF_MONTH=5,DAY_OF_MONTH=28,DAY_OF_YEAR=28,DAY_OF_WEEK=4,DAY_OF_WEEK_IN_MONTH=4,AM_PM=0,HOUR=0,HOUR_OF_DAY=0,MINUTE=0,SECOND=0,MILLISECOND=0,ZONE_OFFSET=32400000,DST_OFFSET=0]
java.util.GregorianCalendar[time=1233154800000,areFieldsSet=true,areAllFieldsSet=true,lenient=true,zone=sun.util.calendar.ZoneInfo[id="Asia/Tokyo",offset=32400000,dstSavings=0,useDaylight=false,transitions=10,lastRule=null],firstDayOfWeek=1,minimalDaysInFirstWeek=1,ERA=1,YEAR=2009,MONTH=0,WEEK_OF_YEAR=5,WEEK_OF_MONTH=5,DAY_OF_MONTH=29,DAY_OF_YEAR=29,DAY_OF_WEEK=5,DAY_OF_WEEK_IN_MONTH=5,AM_PM=0,HOUR=0,HOUR_OF_DAY=0,MINUTE=0,SECOND=0,MILLISECOND=0,ZONE_OFFSET=32400000,DST_OFFSET=0]
java.util.GregorianCalendar[time=1233241200000,areFieldsSet=true,areAllFieldsSet=true,lenient=true,zone=sun.util.calendar.ZoneInfo[id="Asia/Tokyo",offset=32400000,dstSavings=0,useDaylight=false,transitions=10,lastRule=null],firstDayOfWeek=1,minimalDaysInFirstWeek=1,ERA=1,YEAR=2009,MONTH=0,WEEK_OF_YEAR=5,WEEK_OF_MONTH=5,DAY_OF_MONTH=30,DAY_OF_YEAR=30,DAY_OF_WEEK=6,DAY_OF_WEEK_IN_MONTH=5,AM_PM=0,HOUR=0,HOUR_OF_DAY=0,MINUTE=0,SECOND=0,MILLISECOND=0,ZONE_OFFSET=32400000,DST_OFFSET=0]
java.util.GregorianCalendar[time=1233327600000,areFieldsSet=true,areAllFieldsSet=true,lenient=true,zone=sun.util.calendar.ZoneInfo[id="Asia/Tokyo",offset=32400000,dstSavings=0,useDaylight=false,transitions=10,lastRule=null],firstDayOfWeek=1,minimalDaysInFirstWeek=1,ERA=1,YEAR=2009,MONTH=0,WEEK_OF_YEAR=5,WEEK_OF_MONTH=5,DAY_OF_MONTH=31,DAY_OF_YEAR=31,DAY_OF_WEEK=7,DAY_OF_WEEK_IN_MONTH=5,AM_PM=0,HOUR=0,HOUR_OF_DAY=0,MINUTE=0,SECOND=0,MILLISECOND=0,ZONE_OFFSET=32400000,DST_OFFSET=0]
import java.util.*;
import org.apache.commons.lang.time.DateUtils;

public class C2009012401 {
    public static void main(String[] args) {
        Date d = new Date();
        Iterator iter = DateUtils.iterator(d, DateUtils.RANGE_WEEK_SUNDAY);

        while (iter.hasNext()) {
            //System.out.println((Date)iter.next());
            System.out.println((GregorianCalendar)iter.next());
        }
    }
}

で、

java.util.GregorianCalendar[time=1232809200000,areFieldsSet=true,areAllFieldsSet=true,lenient=true,zone=sun.util.calendar.ZoneInfo[id="Asia/Tokyo",offset=32400000,dstSavings=0,useDaylight=false,transitions=10,lastRule=null],firstDayOfWeek=1,minimalDaysInFirstWeek=1,ERA=1,YEAR=2009,MONTH=0,WEEK_OF_YEAR=5,WEEK_OF_MONTH=5,DAY_OF_MONTH=25,DAY_OF_YEAR=25,DAY_OF_WEEK=1,DAY_OF_WEEK_IN_MONTH=4,AM_PM=0,HOUR=0,HOUR_OF_DAY=0,MINUTE=0,SECOND=0,MILLISECOND=0,ZONE_OFFSET=32400000,DST_OFFSET=0]
java.util.GregorianCalendar[time=1232895600000,areFieldsSet=true,areAllFieldsSet=true,lenient=true,zone=sun.util.calendar.ZoneInfo[id="Asia/Tokyo",offset=32400000,dstSavings=0,useDaylight=false,transitions=10,lastRule=null],firstDayOfWeek=1,minimalDaysInFirstWeek=1,ERA=1,YEAR=2009,MONTH=0,WEEK_OF_YEAR=5,WEEK_OF_MONTH=5,DAY_OF_MONTH=26,DAY_OF_YEAR=26,DAY_OF_WEEK=2,DAY_OF_WEEK_IN_MONTH=4,AM_PM=0,HOUR=0,HOUR_OF_DAY=0,MINUTE=0,SECOND=0,MILLISECOND=0,ZONE_OFFSET=32400000,DST_OFFSET=0]
java.util.GregorianCalendar[time=1232982000000,areFieldsSet=true,areAllFieldsSet=true,lenient=true,zone=sun.util.calendar.ZoneInfo[id="Asia/Tokyo",offset=32400000,dstSavings=0,useDaylight=false,transitions=10,lastRule=null],firstDayOfWeek=1,minimalDaysInFirstWeek=1,ERA=1,YEAR=2009,MONTH=0,WEEK_OF_YEAR=5,WEEK_OF_MONTH=5,DAY_OF_MONTH=27,DAY_OF_YEAR=27,DAY_OF_WEEK=3,DAY_OF_WEEK_IN_MONTH=4,AM_PM=0,HOUR=0,HOUR_OF_DAY=0,MINUTE=0,SECOND=0,MILLISECOND=0,ZONE_OFFSET=32400000,DST_OFFSET=0]
java.util.GregorianCalendar[time=1233068400000,areFieldsSet=true,areAllFieldsSet=true,lenient=true,zone=sun.util.calendar.ZoneInfo[id="Asia/Tokyo",offset=32400000,dstSavings=0,useDaylight=false,transitions=10,lastRule=null],firstDayOfWeek=1,minimalDaysInFirstWeek=1,ERA=1,YEAR=2009,MONTH=0,WEEK_OF_YEAR=5,WEEK_OF_MONTH=5,DAY_OF_MONTH=28,DAY_OF_YEAR=28,DAY_OF_WEEK=4,DAY_OF_WEEK_IN_MONTH=4,AM_PM=0,HOUR=0,HOUR_OF_DAY=0,MINUTE=0,SECOND=0,MILLISECOND=0,ZONE_OFFSET=32400000,DST_OFFSET=0]
java.util.GregorianCalendar[time=1233154800000,areFieldsSet=true,areAllFieldsSet=true,lenient=true,zone=sun.util.calendar.ZoneInfo[id="Asia/Tokyo",offset=32400000,dstSavings=0,useDaylight=false,transitions=10,lastRule=null],firstDayOfWeek=1,minimalDaysInFirstWeek=1,ERA=1,YEAR=2009,MONTH=0,WEEK_OF_YEAR=5,WEEK_OF_MONTH=5,DAY_OF_MONTH=29,DAY_OF_YEAR=29,DAY_OF_WEEK=5,DAY_OF_WEEK_IN_MONTH=5,AM_PM=0,HOUR=0,HOUR_OF_DAY=0,MINUTE=0,SECOND=0,MILLISECOND=0,ZONE_OFFSET=32400000,DST_OFFSET=0]
java.util.GregorianCalendar[time=1233241200000,areFieldsSet=true,areAllFieldsSet=true,lenient=true,zone=sun.util.calendar.ZoneInfo[id="Asia/Tokyo",offset=32400000,dstSavings=0,useDaylight=false,transitions=10,lastRule=null],firstDayOfWeek=1,minimalDaysInFirstWeek=1,ERA=1,YEAR=2009,MONTH=0,WEEK_OF_YEAR=5,WEEK_OF_MONTH=5,DAY_OF_MONTH=30,DAY_OF_YEAR=30,DAY_OF_WEEK=6,DAY_OF_WEEK_IN_MONTH=5,AM_PM=0,HOUR=0,HOUR_OF_DAY=0,MINUTE=0,SECOND=0,MILLISECOND=0,ZONE_OFFSET=32400000,DST_OFFSET=0]
java.util.GregorianCalendar[time=1233327600000,areFieldsSet=true,areAllFieldsSet=true,lenient=true,zone=sun.util.calendar.ZoneInfo[id="Asia/Tokyo",offset=32400000,dstSavings=0,useDaylight=false,transitions=10,lastRule=null],firstDayOfWeek=1,minimalDaysInFirstWeek=1,ERA=1,YEAR=2009,MONTH=0,WEEK_OF_YEAR=5,WEEK_OF_MONTH=5,DAY_OF_MONTH=31,DAY_OF_YEAR=31,DAY_OF_WEEK=7,DAY_OF_WEEK_IN_MONTH=5,AM_PM=0,HOUR=0,HOUR_OF_DAY=0,MINUTE=0,SECOND=0,MILLISECOND=0,ZONE_OFFSET=32400000,DST_OFFSET=0]
import java.util.*;
import org.apache.commons.lang.time.DateUtils;

public class C2009012402 {
    public static void main(String[] args) {
        GregorianCalendar c = new GregorianCalendar();
        Iterator iter = DateUtils.iterator((Object)c, DateUtils.RANGE_WEEK_SUNDAY);

        while (iter.hasNext()) {
            System.out.println((GregorianCalendar)iter.next());
        }
    }
}

で、

java.util.GregorianCalendar[time=1232809200000,areFieldsSet=true,areAllFieldsSet=true,lenient=true,zone=sun.util.calendar.ZoneInfo[id="Asia/Tokyo",offset=32400000,dstSavings=0,useDaylight=false,transitions=10,lastRule=null],firstDayOfWeek=1,minimalDaysInFirstWeek=1,ERA=1,YEAR=2009,MONTH=0,WEEK_OF_YEAR=5,WEEK_OF_MONTH=5,DAY_OF_MONTH=25,DAY_OF_YEAR=25,DAY_OF_WEEK=1,DAY_OF_WEEK_IN_MONTH=4,AM_PM=0,HOUR=0,HOUR_OF_DAY=0,MINUTE=0,SECOND=0,MILLISECOND=0,ZONE_OFFSET=32400000,DST_OFFSET=0]
java.util.GregorianCalendar[time=1232895600000,areFieldsSet=true,areAllFieldsSet=true,lenient=true,zone=sun.util.calendar.ZoneInfo[id="Asia/Tokyo",offset=32400000,dstSavings=0,useDaylight=false,transitions=10,lastRule=null],firstDayOfWeek=1,minimalDaysInFirstWeek=1,ERA=1,YEAR=2009,MONTH=0,WEEK_OF_YEAR=5,WEEK_OF_MONTH=5,DAY_OF_MONTH=26,DAY_OF_YEAR=26,DAY_OF_WEEK=2,DAY_OF_WEEK_IN_MONTH=4,AM_PM=0,HOUR=0,HOUR_OF_DAY=0,MINUTE=0,SECOND=0,MILLISECOND=0,ZONE_OFFSET=32400000,DST_OFFSET=0]
java.util.GregorianCalendar[time=1232982000000,areFieldsSet=true,areAllFieldsSet=true,lenient=true,zone=sun.util.calendar.ZoneInfo[id="Asia/Tokyo",offset=32400000,dstSavings=0,useDaylight=false,transitions=10,lastRule=null],firstDayOfWeek=1,minimalDaysInFirstWeek=1,ERA=1,YEAR=2009,MONTH=0,WEEK_OF_YEAR=5,WEEK_OF_MONTH=5,DAY_OF_MONTH=27,DAY_OF_YEAR=27,DAY_OF_WEEK=3,DAY_OF_WEEK_IN_MONTH=4,AM_PM=0,HOUR=0,HOUR_OF_DAY=0,MINUTE=0,SECOND=0,MILLISECOND=0,ZONE_OFFSET=32400000,DST_OFFSET=0]
java.util.GregorianCalendar[time=1233068400000,areFieldsSet=true,areAllFieldsSet=true,lenient=true,zone=sun.util.calendar.ZoneInfo[id="Asia/Tokyo",offset=32400000,dstSavings=0,useDaylight=false,transitions=10,lastRule=null],firstDayOfWeek=1,minimalDaysInFirstWeek=1,ERA=1,YEAR=2009,MONTH=0,WEEK_OF_YEAR=5,WEEK_OF_MONTH=5,DAY_OF_MONTH=28,DAY_OF_YEAR=28,DAY_OF_WEEK=4,DAY_OF_WEEK_IN_MONTH=4,AM_PM=0,HOUR=0,HOUR_OF_DAY=0,MINUTE=0,SECOND=0,MILLISECOND=0,ZONE_OFFSET=32400000,DST_OFFSET=0]
java.util.GregorianCalendar[time=1233154800000,areFieldsSet=true,areAllFieldsSet=true,lenient=true,zone=sun.util.calendar.ZoneInfo[id="Asia/Tokyo",offset=32400000,dstSavings=0,useDaylight=false,transitions=10,lastRule=null],firstDayOfWeek=1,minimalDaysInFirstWeek=1,ERA=1,YEAR=2009,MONTH=0,WEEK_OF_YEAR=5,WEEK_OF_MONTH=5,DAY_OF_MONTH=29,DAY_OF_YEAR=29,DAY_OF_WEEK=5,DAY_OF_WEEK_IN_MONTH=5,AM_PM=0,HOUR=0,HOUR_OF_DAY=0,MINUTE=0,SECOND=0,MILLISECOND=0,ZONE_OFFSET=32400000,DST_OFFSET=0]
java.util.GregorianCalendar[time=1233241200000,areFieldsSet=true,areAllFieldsSet=true,lenient=true,zone=sun.util.calendar.ZoneInfo[id="Asia/Tokyo",offset=32400000,dstSavings=0,useDaylight=false,transitions=10,lastRule=null],firstDayOfWeek=1,minimalDaysInFirstWeek=1,ERA=1,YEAR=2009,MONTH=0,WEEK_OF_YEAR=5,WEEK_OF_MONTH=5,DAY_OF_MONTH=30,DAY_OF_YEAR=30,DAY_OF_WEEK=6,DAY_OF_WEEK_IN_MONTH=5,AM_PM=0,HOUR=0,HOUR_OF_DAY=0,MINUTE=0,SECOND=0,MILLISECOND=0,ZONE_OFFSET=32400000,DST_OFFSET=0]
java.util.GregorianCalendar[time=1233327600000,areFieldsSet=true,areAllFieldsSet=true,lenient=true,zone=sun.util.calendar.ZoneInfo[id="Asia/Tokyo",offset=32400000,dstSavings=0,useDaylight=false,transitions=10,lastRule=null],firstDayOfWeek=1,minimalDaysInFirstWeek=1,ERA=1,YEAR=2009,MONTH=0,WEEK_OF_YEAR=5,WEEK_OF_MONTH=5,DAY_OF_MONTH=31,DAY_OF_YEAR=31,DAY_OF_WEEK=7,DAY_OF_WEEK_IN_MONTH=5,AM_PM=0,HOUR=0,HOUR_OF_DAY=0,MINUTE=0,SECOND=0,MILLISECOND=0,ZONE_OFFSET=32400000,DST_OFFSET=0]