Java add a list to class and modification -

i have problem list. adds list class. in class list more items added. when want display list of class not have items.

add people mysqlcategorydao -> modify in mysqlcategorydao -> return people in class model.

public class model {      public list<category> people = new vector<category>();      public list<category> getpeople() {          (category person : people) {             system.out.println(person.getname());  //no data         }         return new arraylist<category>(people);     }      public void load() throws exception {          daofactory factory = daofactory.getfactory(daofactory.mysql);          new mysqlcategorydao(job.select,people).execute();     }  } 

class in modifies list

public class mysqlcategorydao extends swingworker<void, category> implements categorydao{      private job job;     public list<category> list;       public mysqlcategorydao(job job, list<category> list){         this.job = job;         this.list = list;     }     @override     public  void doinbackground() throws exception {         // todo auto-generated method stub          if(job == job.select){             getcategory();             system.out.println("table selected");         }                return null;     }        public list<category> getcategory() throws sqlexception     {         connection conn = database.getinstance().getconnection();          system.out.println(conn);          string sql = "select id, name kategorie";         statement selectstatement =  conn.createstatement();         resultset results = selectstatement.executequery(sql);          while(results.next())         {             int id = results.getint("id");             string name = results.getstring("name");              ///category category = new category(id, name);             //cat.add(category);             publish(new category(id,name));             system.out.println("test");         }         results.close();         selectstatement.close();          return null;      }     public  void process(list<category> chunks){         list.addall(chunks);          (category person : list) {             system.out.println(person.getname()); //data show ok!         }     } } 

when want refer list of model did not get.

public void loaddata() {          mysqlcategorydao dao = new mysqlcategorydao(null,null);         people = model.getpeople();          (category person : people) {             tablemodel                     .addrow(new object[] { person.getid(), person.getname() }); //no data         }          people.clear();      }