JscrollPane disappears after adding it to another class which extends to JPanel

Question

i have a class A which extends from JPanel which contains a JScrollpanel.

SearchTapViewImpl extends JPanel implements SearchTapView {

          SearchTapViewImpl(){
                JPanel panel = new JPanel();
                // ... add stuff to this panel

                JScrollPane scrollPane = new JScrollPane(panel)
                //create stuff
                add(anotherPanel, BorderLayout.NORTH);
                add(scrollpanel, BorderLayout.CENTER);
          }
}

now i have a controller class which extends from JPanel too which only adds an instance of SearchTapViewImpl

public class SearchTapController extends JPanel{

       view = new SearchTapViewImpl();
       // stuff
       add((Component)view, BorderLayout.NORTH);
}

now i have a class which extends from JFrame and contains a JTabbedPane The thing is when i add a instance of SearchTapController, which contains an instance of SearchTapViewImpl, the scrollpane is not visible. Instead when i add SearchTapViewImpl to the Jframe class the scrolls are visible. Why is not visible when i add it through the SearchTapController?

// NOT WORKING EXAMPLE
public class StartGUI extends JFrame {
    tabbedPane = new JTabbedPane();
    tabbedPane.addTab("Search", new SearchTapController() ); 
}

//  WORKING EXAMPLE
public class StartGUI extends JFrame {
    tabbedPane = new JTabbedPane();
    tabbedPane.addTab("Search", SearchTapViewImpl() ); 
}

Answer 1

add((Component)view, BorderLayout.NORTH);

When you add a component to the "NORTH" of the BorderLayout , the component is always displayed at its preferred height so there is no need for the scollbar to appear.

Try adding it to the BorderLayout.CENTER .