javabeans - Java: Trouble with wildcards/generics -

this question has answer here:

• what pecs (producer extends consumer super)? 8 answers

i struggling using wildcards/generics. i'm trying create filemanager utility class can accept custom java beans , write read/write bean file. give example imagine have interface called data implemented recipedata , demographicdata. i'm using super csv convert csv file java bean. here read method based on tutorial code found super csv.

public interface data { method declarations } public class recipedata implements data { class stuff goes here } public class demographicdata implements data { class stuff goes here }  final public class filemanager {     public static void parsecsvfile(string filename, cellprocessor[] processors, string[] namemappings, list<? extends data> container) {          icsvbeanreader beanreader = null;         try {             beanreader = new csvbeanreader(new filereader(filename), csvpreference.standard_preference);              data data;             while((data = beanreader.read(data.class, namemappings, processors)) != null ) {                 container.add(data);             }         } {             if (beanreader != null) {                 beanreader.close();             }         }     } } 

currently, i'm getting following error:

the method add(capture#1-of ? extends data) in type list not applicable arguments (data)

i'm not sure i'm doing possible. idea is, container passed can of type recipedata or demographicdata. think 1 problem data should of 2 types.

can give feedback on how potentially fix or if it'll work?

edit: i'm not sure possible.

instead of using wildcard list<? extends data> container, use list<data> container.