java - Comparator not sorted my class with dates -

i have class day,month. insert random dates , after sorted looks that? why?

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i getting "time" getting database , return data arraylist code:

public arraylist<clockmodel> getday(string workname){         try {             open();             arraylist<clockmodel> list = new arraylist<clockmodel>();             cursor c = null;             c = mydb.query(table_day, null,"workname = ?", new string[] {workname}, null, null, null);             while (c.movetonext()) {                 clock clock = new clock(                         c.getint(0), //id                         c.getstring(1),//workname                         c.getint(2), //dateday                         c.getint(3),//datemouth                         c.getint(4),//dateyear                 );                   collections.sort(list,datecompare);                     list.add(clock);                     }                    return list;         } catch (exception e) {             return null;         }finally{             close();         }     }          comparator<clockmodel> datecompare = new comparator<clockmodel>() {          @override         public int compare(clockmodel o1, clockmodel o2) {              int dd1 = o1.getdateday();             int mm1 = o1.getdatemonth();              int dd2 = o2.getdateday();             int mm2 = o2.getdatemonth();              if (mm1 > mm2) {                 return 1;             } else if (mm1 < mm2) {                 return -1;             } else { // ==                  if (dd1 > dd2) {                     return 1;                 } else if (dd1 < dd2) {                     return -1;                 } else {                     return 0;                 }             }         }     };  

the compare method looks fine. sure bug here? if yours class clockmodel, suggest double check it=)

and btw, can simplify code using integer.compare(int, int) this:

comparator<clockmodel> datecompare = new comparator<clockmodel>() {      @override     public int compare(clockmodel o1, clockmodel o2) {          int monthcompare = integer.compare(o1.getdatemonth(), o2.getdatemonth());         int daycompare = integer.compare(o1.getdateday(), o2.getdateday());          return (monthcompare != 0) ? monthcompare : daycompare;      } }