CardLayout contains multiple widgets, each fit to the container, where only a single widget can be visible at any given time. This layout style is most commonly used for wizards, tab implementations, etc.
The CardLayout's focal method is setActiveItem. Since only one panel is displayed at a time, the only way to move from one panel to the next is by calling setActiveItem the next panel to display. The layout itself does not provide a mechanism for handling this navigation, so that functionality must be provided by the developer.
As an alternative, CardPanel is a LayoutContainer subclass that uses a CardLayout internally. It provides a setActiveItem method for changing the active item.