Core Swing Components - The Definitive Guide to Java Swing - page 65

Figure 4-1. JComponent class hierarchy diagram
■ Note JComponent extends from the Container class, but most of the JComponent subclasses aren't
themselves containers of other components. To see if a particular Swing component is truly a container,
check the BeanInfo for the class to see if the isContainer property is set to true . To get the BeanInfo
for a class, ask the Introspector .