Call Us Toll-Free
(877) 256-0328
Outside USA
1 - (201) 505-0430
Site Map
|
|
|
|
|
|
How to Use Internal Frames (The Java™ Tutorials >
Creating a GUI with JFC/Swing > Using Swing Components)
How to Use Internal Frames
Home Page
>
Creating a GUI with JFC/Swing
>
Using Swing Components
How to Use Internal Frames
With the
JInternalFrame class
you can display a
JFrame-like window
within another window.
Usually, you add internal frames
to a desktop pane.
The desktop pane, in turn,
might be used as the content pane of a JFrame.
The desktop pane is an instance of
JDesktopPane, which is a subclass of
JLayeredPane
that has added API for managing multiple overlapping internal frames.
You should consider carefully whether to base your program's GUI
around frames or internal frames.
Switching from internal frames to frames
or vice versa is not necessarily a simple task.
By experimenting with both frames and internal frames,
you can get an idea of the tradeoffs involved
in choosing one over the other.
Here is a picture of an application
that has two internal frames
(one of which is iconified)
inside a regular frame:
Try this:
-
Click the Launch button to run InternalFrameDemo using
Java™ Web Start (download JDK 6).
Alternatively, to compile and run the example yourself,
consult the
example index.
- Create new internal frames
using the Create item in the Document menu.
Each internal frame comes up 30 pixels lower and to the right of
the place where the previous internal frame first appeared.
This functionality is implemented in the
MyInternalFrame class,
which is the custom subclass of JInternalFrame.
The following code,
taken from
InternalFrameDemo.java,
creates the desktop and internal frames in the previous example.
...//In the constructor of InternalFrameDemo, a JFrame subclass:
desktop = new JDesktopPane();
createFrame(); //Create first window
setContentPane(desktop);
...
//Make dragging a little faster but perhaps uglier.
desktop.setDragMode(JDesktopPane.OUTLINE_DRAG_MODE);
...
protected void createFrame() {
MyInternalFrame frame = new MyInternalFrame();
frame.setVisible(true);
desktop.add(frame);
try {
frame.setSelected(true);
} catch (java.beans.PropertyVetoException e) {}
}
...//In the constructor of MyInternalFrame, a JInternalFrame subclass:
static int openFrameCount = 0;
static final int xOffset = 30, yOffset = 30;
public MyInternalFrame() {
super("Document #" + (++openFrameCount),
true, //resizable
true, //closable
true, //maximizable
true);//iconifiable
//...Create the GUI and put it in the window...
//...Then set the window size or call pack...
...
//Set the window's location.
setLocation(xOffset*openFrameCount, yOffset*openFrameCount);
}
The code for using internal frames
is similar in many ways to the code for using regular Swing frames.
Because internal frames have root panes,
setting up the GUI for a JInternalFrame
is very similar to setting up the GUI for a JFrame.
JInternalFrame also provides
other API,
such as pack,
that makes it similar to JFrame.
Note: Just as for a regular frame,
you must invoke setVisible(true) or show()
on an internal frame to display it.
The internal frame does not appear until you explicitly make it visible.
Internal frames are not windows or top-level containers, however,
which makes them different from frames.
For example, you must add an internal frame
to a container (usually a JDesktopPane);
an internal frame cannot be the root of a containment hierarchy.
Also, internal frames do not generate window events.
Instead, the user actions that would
cause a frame to fire window events
cause an internal frame to fire internal frame events.
Because internal frames are implemented with platform-independent code,
they add some features that frames cannot give you.
One such feature is that
internal frames give you more control over
their state and capabilities than frames do.
You can programatically iconify or maximize an internal frame.
You can also specify what icon goes in the internal frame's
title bar.
You can even specify whether the internal frame
has the window decorations
to support resizing, iconifying, closing, and maximizing.
Another feature is that internal frames
are designed to work within desktop panes.
The JInternalFrame API
contains methods such as moveToFront
that work only if the internal frame's container
is a layered pane such as a JDesktopPane.
If you have built any programs using JFrame
and the other Swing components,
then you already know a lot
about how to use internal frames.
The following list
summarizes the rules for using internal frames.
For additional information, see
How to Make Frames
and
The JComponent Class.
- You must set the size of the internal frame.
- If you do not set the size of the internal frame,
it will have zero size
and thus never be visible.
You can set the size using one of the following methods:
setSize,
pack,
or setBounds.
- As a rule, you should set the location
of the internal frame.
- If you do not set the location of the internal frame,
it will come up at 0,0 (the upper left of its container).
You can use the
setLocation or setBounds
method to specify the upper left point of the internal frame,
relative to its container.
- To add components to an internal frame,
you add them to the internal frame's content pane.
- This is exactly like the
JFrame situation.
See Adding Components to the Content
Pane
for details.
- Dialogs that are internal frames
should be implemented using
JOptionPane or
JInternalFrame,
not JDialog.
- To create a simple dialog,
you can use the
JOptionPane
showInternalXxxDialog methods,
as described in
How to Make Dialogs.
- You must add an internal frame to a container.
- If you do not add the internal frame to a container
(usually a
JDesktopPane),
the internal frame will not appear.
- You need to call
show
or setVisible on internal frames.
- Internal frames are invisible by default.
You must invoke
setVisible(true)
or show() to make them visible.
- Internal frames fire internal frame events,
not window events.
- Handling internal frame events is almost identical
to handling window events.
See How
to Write an Internal Frame Listener for more information.
Performance tip:
When a desktop has many internal frames,
the user might notice that moving them seems slow.
Outline dragging
is one way to avoid this problem.
With outline dragging,
only the outline of the internal frame is painted
at the current mouse position while the internal frame's being dragged.
The internal frame's innards
are not repainted at a new position until dragging stops.
The default behavior (called live dragging)
is to reposition and repaint some or all of internal frame continuously
while it is being moved;
this can be slow if the desktop has many internal frames.
Use the JDesktopPane method
setDragMode*
to specify outline dragging.
For example:
desktop.setDragMode(JDesktopPane.OUTLINE_DRAG_MODE);
The following tables list the commonly used
JInternalFrame constructors and methods,
as well as a few methods that JDesktopPane provides.
Besides the API listed in this section,
JInternalFrame inherits useful API from
its superclasses,
JComponent,
Component, and
Container.
See The JComponent Class
for lists of methods from those classes.
Like JInternalFrame,
JDesktopPane descends from
JComponent,
and thus provides the methods described in
The JComponent Class.
Because JDesktopPane extends
JLayeredPane,
it also supports the methods described in
The Layered Pane API.
The API for using internal frames falls into these categories:
Creating the Internal Frame
| Constructor or Method
|
Purpose
|
JInternalFrame()
JInternalFrame(String)
JInternalFrame(String, boolean)
JInternalFrame(String, boolean, boolean)
JInternalFrame(String, boolean, boolean, boolean)
JInternalFrame(String, boolean, boolean, boolean, boolean) |
Create a JInternalFrame instance.
The first argument specifies the title (if any)
to be displayed by the internal frame.
The rest of the arguments specify
whether the internal frame should contain decorations allowing
the user to
resize, close, maximize, and iconify the internal frame
(specified in that order).
The default value for each boolean argument is false,
which means that the operation
is not allowed.
|
static int showInternalConfirmDialog(Component, Object)
static String showInternalInputDialog(Component, Object)
static Object showInternalMessageDialog(Component, Object)
static int showInternalOptionDialog(Component, Object, String, int, int, Icon, Object[], Object) |
Create a JInternalFrame
that simulates a dialog.
See How to Make Dialogs for details.
|
The following examples use internal frames.
Because internal frames are similar to regular frames,
you should also look at
Examples that Use Frames.
| Example
|
Where Described
|
Notes
|
MyInternalFrame
|
This page.
|
Implements an internal frame
that appears at an offset to the previously created
internal frame.
|
InternalFrameDemo
|
This page.
|
Lets you create internal frames
(instances of MyInternalFrame)
that go into the application's JDesktopPane.
|
InternalFrameEventDemo
|
How to Write
an Internal Frame Listener
|
Demonstrates listening for internal frame events.
Also demonstrates positioning internal frames within a desktop pane.
|
|
