> . . . the latter versions of the api do not require you do not need to worry
Does Java allow double negatives?
From the JFrame API:
The JFrame class is slightly incompatible with Frame. Like all other JFC/Swing top-level containers, a JFrame contains a JRootPane as its only child. The content pane provided by the root pane should, as a rule, contain all the non-menu components displayed by the JFrame. This is different from the AWT Frame case. As a conveniance add and its variants, remove and setLayout have been overridden to forward to the contentPane as necessary. This means you can write:frame.add(child);
And the child will be added to the contentPane.