In swing, following components are considered as heavyweight:
JFrame, JDialog, JApplet, JWindow
All the heavyweight components implement RootPaneContainer Interface and hence delegate their operations to JRootPane.
Following diagram shows the class hierarchy of JRootPane:
As shown in the diagram, JRootPane contains JLayeredPane. JLayeredPane contains optional JMenuBar and JContentPane.
And on top of all, there is JGlassPane.
The role of each pane is as follows:
JRootPane:
It is the base pane on which all other swing containers reside
And on top of all, there is JGlassPane.
The role of each pane is as follows:
JRootPane:
It is the base pane on which all other swing containers reside
JLayeredPane:
JMenuBar and JContentPane reside on JLayeredPane
There can be multiple layered panes for graphics application. For instance, overlapping shapes is internally implemented by swing by creating overlapping JLayeredPanes.
JMenuBar:
Contains the menu bar for Swing application
ContentPane:
It contains the actual components. LayoutManager operates in this layer to determine shape, size and position of the components.
JGlassPane:
It is positioned above all the panes. It allows programmer to draw on top of all the underlying components. It also deals with mouse movements for Swing components.
