Java: Containers
Top-level Containers - window, applet, dialog, ...
All elements of a user interface
must be added to the content pane of
a top-level container in Java 2.
You can also set the content pane to
a new JPanel (but not a split, tabbed, or scroll pane) with
myFrame.setContentPane(myPanel), adding components
to myPanel.
Use JFrame - Window for a window,
and JApplet for an applet.
Another type of top-level container is a dialog, which can
be created with JDialog, but it is usually easier
to use Dialogs.
You will use these three types of top-level containers:
- Windows (JFrame) have a title bar with close and iconifying buttons.
- Dialogs (JOptionPane, ProgressMonitor, JDialog, JFileChooser, JColorChooser) can easily be created.
To get a print dialog you should use methods in the Toolkit class.
- Applets (JApplet).
Intermediate Containers
To group components
together put them on a JPanel - Container,
where you can set the layout, background, and borders.
You can also use a JPanel for graphics, but then don't
also use it as a component container.
There are other specialized containers that act more like
components, for example, JScrollPane, ... .
After you have added your components to a panel (eg, content),
set the content pane of the top-level container (eg, myApplet)
to this panel
with myApplet.setContentPane(content);.
Here is a list of the intermediate containers, though you may never use more than JPanel.
- Panels (JPanel) are used to group components, or provide a drawing area.
- Scroll panes (JScrollPane) for areas that are too big to display entirely.
This will have vertical and horizontal scrollbars to move in.
- Split panes (JSplitPane) allow the user to change the relative size of
two panes.
- Tabbed panes (JTabbedPane) For displaying panes with tabs.
- Tool bars (JToolBar) for displaying toolbars.
- Other: JInternalFrame (if you need a window inside a window).
Layouts
The way the components are arranged in a container
and the way the components are rearranged when
a container is resized is determined by the container's
Layouts.