What should u know about top level containers and general purpose

As a developer of GUI, what should u know about top level containers and general purpose containers?

A container is a collection of related components, which allows other components to be nested inside it. In application with JFrame, we attatch components to the content pane – a container.

Container are classified into two broad categories that are Top Level containers and

 General Purpose Containers
Top level containers can contain (add) other containers as well as basic components (buttons, labels etc) while general purpose containers are typically used to collect basic components and are added to top level containers. General purpose containers cannot exist alone they must be added to top level containers

Examples of top level container are JFrame, Dialog and Applet etc. Our application uses one of these. Examples of general purpose container are JPanel, Toolbar and ScrollPane etc.