|
|
|
|
|
|
|
Component classes are subclasses of the
Component class; container classes are subclasses of the
Container class. The following shows the locations of the
Component and Container classes in the Java class hierarchy, as well as the locations of other key
classes, JFrame, JApplet, JComponent, and
JPanel, which are the focus of this chapter, Chapter 43, and
Chapter 39.
The class hierarchy shows that all containers are components, but not all
components are containers. It so happens that all the components used in
this book are containers because they have Container as a
superclass.
*-----------* | Object | *-----------* ^ | *-----------* | Component | *-----------* ^ | | *-----------* | Container | *-----------* ^ ^ | *---------------------------*--------------------------* | | | *-----------* *-----------* *------------* | Window | | Panel | | JComponent | *-----------* *-----------* *------------* ^ ^ ^ | | | *-----------* *-----------* *------------* | Frame | | Applet | | JPanel | *-----------* *-----------* *------------* | ^ | | *-----------* *-----------* | JFrame | | JApplet | *-----------* *-----------*