public static void getPreDay() throws ParseException{

    String dateStr="2013-1-1";

    Date date=formatToDate(dateStr, "yyyy-MM-dd");

    System.out.println(dateStr);

   

    Calendar calendar = Calendar.getInstance();

    calendar.setTime(date);

    calendar.add(Calendar.DATE, -1);    //得到前一天

    //calendar.add(Calendar.MONTH, -1);    //得到前一个月

    System.out.println(formatToString(calendar.getTime(), "yyyy-MM-dd"));

}

public static Date formatToDate(String strDate,String format) throws ParseException{

    DateFormat df=new SimpleDateFormat(format);

    return df.parse(strDate);

}

public static String formatToString(Date date,String format){

    DateFormat df=new SimpleDateFormat(format);

    return df.format(date);

}