PersianCalendar extends AbstractCalendar { @Override public DateTimeUnit minusDays( DateTimeUnit dateTimeUnit, int days ) { int curYear = dateTimeUnit.getYear(); int curMonth = dateTimeUnit.getMonth(); int curDay = dateTimeUnit.getDay(); int dayOfWeek = dateTimeUnit.getDayOfWeek(); int newDays = days; while ( newDays != 0 ) { curDay--; if ( curDay == 0 ) { curMonth--; if ( curMonth == 0 ) { curYear--; curMonth = 12; } curDay = getDaysFromMap( curYear, curMonth ); } dayOfWeek--; if ( dayOfWeek == 0 ) { dayOfWeek = 7; } newDays--; } return new DateTimeUnit( curYear, curMonth, curDay, dayOfWeek ); }  static Calendar getInstance(); @Override String name(); @Override DateTimeUnit toIso( DateTimeUnit dateTimeUnit ); @Override DateTimeUnit fromIso( Date date ); @Override DateTimeUnit fromIso( DateTimeUnit dateTimeUnit ); @Override DateInterval toInterval( DateTimeUnit dateTimeUnit, DateIntervalType type, int offset, int length ); @Override int daysInYear( int year ); @Override int daysInMonth( int year, int month ); @Override int weeksInYear( int year ); @Override int isoWeek( DateTimeUnit dateTimeUnit ); @Override int week( DateTimeUnit dateTimeUnit ); @Override int isoWeekday( DateTimeUnit dateTimeUnit ); @Override int weekday( DateTimeUnit dateTimeUnit ); @Override String nameOfMonth( int month ); @Override String shortNameOfMonth( int month ); @Override String nameOfDay( int day ); @Override String shortNameOfDay( int day ); @Override DateTimeUnit minusYears( DateTimeUnit dateTimeUnit, int years ); @Override DateTimeUnit minusMonths( DateTimeUnit dateTimeUnit, int months ); @Override DateTimeUnit minusWeeks( DateTimeUnit dateTimeUnit, int weeks ); @Override DateTimeUnit minusDays( DateTimeUnit dateTimeUnit, int days ); @Override DateTimeUnit plusYears( DateTimeUnit dateTimeUnit, int years ); @Override DateTimeUnit plusMonths( DateTimeUnit dateTimeUnit, int months ); @Override DateTimeUnit plusWeeks( DateTimeUnit dateTimeUnit, int weeks ); @Override DateTimeUnit plusDays( DateTimeUnit dateTimeUnit, int days ); @Override DateTimeUnit isoStartOfYear( int year );  }
@Test public void testMinusDays() { DateTimeUnit dateTimeUnit = new DateTimeUnit( 1371, 1, 1 ); DateTimeUnit testDateTimeUnit = calendar.minusDays( dateTimeUnit, 1 ); assertEquals( 1370, testDateTimeUnit.getYear() ); assertEquals( 12, testDateTimeUnit.getMonth() ); assertEquals( 30, testDateTimeUnit.getDay() ); testDateTimeUnit = calendar.minusDays( dateTimeUnit, 366 ); assertEquals( 1370, testDateTimeUnit.getYear() ); assertEquals( 1, testDateTimeUnit.getMonth() ); assertEquals( 1, testDateTimeUnit.getDay() ); dateTimeUnit = new DateTimeUnit( 1371, 7, 1 ); testDateTimeUnit = calendar.minusDays( dateTimeUnit, 1 ); assertEquals( 1371, testDateTimeUnit.getYear() ); assertEquals( 6, testDateTimeUnit.getMonth() ); assertEquals( 31, testDateTimeUnit.getDay() ); dateTimeUnit = new DateTimeUnit( 1371, 8, 1 ); testDateTimeUnit = calendar.minusDays( dateTimeUnit, 1 ); assertEquals( 1371, testDateTimeUnit.getYear() ); assertEquals( 7, testDateTimeUnit.getMonth() ); assertEquals( 30, testDateTimeUnit.getDay() ); }