问在Java中比较字符串类型的日期减去几天

EN

public class DateExample {

    public static void main(String[] args) {
        System.out.println(isWithin("2014-01-01", -7));
        System.out.println(isWithin("2014-01-03", -7));
        System.out.println(isWithin("2013-12-27", -7));
    }

    public static boolean isWithin(String date, int days){
        SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd");
        Date dateProvided = null;
        try {
            dateProvided = format.parse(date);
        } catch (ParseException e) {
            e.printStackTrace();
        } 

        Calendar calendar = Calendar.getInstance();
        calendar.add(Calendar.DAY_OF_MONTH, days);
        calendar.set(Calendar.HOUR, 12);
        calendar.set(Calendar.MINUTE, 0);
        calendar.set(Calendar.SECOND, 0);
        calendar.set(Calendar.MILLISECOND, 0);
        Date comparisonDate = calendar.getTime();

        return comparisonDate.equals(dateProvided);
    }
} 

// © 2013 Basil Bourque. This source code may be used freely forever by anyone taking full responsibility for doing so.
// import org.joda.time.*;

String string = "2011-02-03";
LocalDate localDate = new LocalDate( string );
LocalDate sevenDaysAgo = LocalDate.now().minusDays( 7 );
boolean isThatDateMoreThanSevenDaysAgo = localDate.isBefore( sevenDaysAgo );

System.out.println( "localDate: " + localDate );
System.out.println( "sevenDaysAgo: " + sevenDaysAgo );
System.out.println( "isThatDateMoreThanSevenDaysAgo: " + isThatDateMoreThanSevenDaysAgo );

localDate: 2011-02-03
sevenDaysAgo: 2013-12-26
isThatDateMoreThanSevenDaysAgo: true