A good answer might be:

A GUI component constructed from a container class is expected to contain other GUI components.

JComponent class

Objects of the Container class or of classes based on Container have common characteristics. They can contain components, they themselves can be placed inside containers, they can be displayed on the monitor, they generate events, they register event listeners, and so on. Since all Swing classes have Container as an ancestor, all Swing objects have these characteristics.

There are more Swing classes than those shown. For example there are several button types derived from AbstractButton.


What letter starts the name of many Swing classes?