Implementing a generic list that can hold multiple data types in Java/JavaFX

Question

I need to develop a list of libraries that will hold multiple library types. For example, the library can be a library of videos, or a library of photos. I want to follow the MVC design pattern using JavaFX if this is of relevance. Please see the UML diagram below in reference to my question:

Figure 1

So I figured I'd use a generic type for the list in my Library Model like this:

public class LibraryModel<T> {
    private List<T> aList;
}

However, this won't work because when I instantiate the list of libraries, I need to specify a type. So in this way, I can only specify either a Photo or a Video library as a list, not both.

I tried to introduce a generic type called "Library" that will be listed in the list (as a superclass) to be extended by the PhotoController/VideoController:

Figure 2

public class LibraryModel {
    private List<Library> aList;
}

In figure 2, I could create a list of generic libraries. But how will this affect my ability to perform specific photo/video tasks? Let's assume I have the following methods:

Superclass methods:

displayAll()
add()
remove()

Photo library methods:

displaySlideShow()

Video library methods:

playVideo()

By storing the libraries as the superclass, how will I be able to call the specific methods of the other library types? Is this even legal?

Please go easy on me, I'm still learning Java, thanks in advance.

Answer 1

Use abstract class

the Library.

abstract class Library {

}

then create child classes.

the photo library.

class PhotoLibrary extends Library {

     displaySlideShow(){

     }   
}

the video library.

class VideoLibrary extends Library {

        playVideo() {

        }

}

in main class or another you can use them.

private List<Library> aList;
aList.add(new PhotoLibrary());
VideoLibrary l2 = new VideoLibrary();
aList.add(l2);

then you can call available methods using,

Library l = aList(i);
if(l instanceof PhotoLibrary) {
     PhotoLibrary pl = (PhotoLibrary)l;
     pl.displaySlideShow();
}
else if(l instanceof VideoLibrary) {
     VideoLibrary vl = (VideoLibrary)l;
     vl.playVideo();
}