Generics Question

[henri henri]

In the method below, do I need to use <String> as it is in the method declaration of the second example of the same method?

 
 
  public final List getTitlesByActorName(String name) {
       List<String>list = new ArrayList<String>();
       Collection values = filmContainer.values(); 
          for(Iterator<FilmBean>it = values.iterator(); it.hasNext() :wink:  { 
              FilmBean filmBean = it.next();  
              String actor_name = filmBean.getActorName();
              if(actor_name.equals(name)) {
                  String film_name = filmBean.getName();
                  list.add(film_name);
                  }
             }
      return list;
   }
 
---------------------------------------------------------------------------
  public final List<String> getTitlesByActorName(String name) {
       List<String>list = new ArrayList<String>();
       Collection values = filmContainer.values(); 
          for(Iterator<FilmBean>it = values.iterator(); it.hasNext() :wink:  { 
              FilmBean filmBean = it.next();  
              String actor_name = filmBean.getActorName();
              if(actor_name.equals(name)) {
                  String film_name = filmBean.getName();
                  list.add(film_name);
                  }
             }
      return list;
   }
 

[Tony Morris]

You don't need to.
You might return a List<?> or a List<? super String>.
There isn't much point to returning a List<? extends String> even though the compiler will permit it. It's all up to the definition of the contract that you are providing to your clients.

[Jesper de Jong]

Note that java.lang.String is a final class (you can't subclass it), so List<? extends String> or List<? super String> isn't necessary.

Just use List<String> as in your second version of the method.

[Tony Morris]

Originally posted by Jesper de Jong:
Note that java.lang.String is a final class (you can't subclass it), so List<? extends String> or List<? super String> isn't necessary.

Just use List<String> as in your second version of the method.

List<? extends String> makes no sense.
List<? super String> may certainly be sensible in some given context.
I said that already.