How do I open a JInternalFrame centered in a JDesktopPane?

Question

I am adding a bunch of JInternalFrames into a JDesktopPane, as the user selects to open various features through the menus. But I would like the internal frames to open centered in the desktop pane, as opposed to the upper left, where they seem to default.

How can I specify that the JInternalFrames open centered, or move them to the center after opening?

jDesktopPane.add(jInternalFrame); // jInternalFrame is not centered!

Answer 1

For reference, here is the solution I used, based on dogbane's advice:

Dimension desktopSize = desktopPane.getSize();
Dimension jInternalFrameSize = jInternalFrame.getSize();
jInternalFrame.setLocation((desktopSize.width - jInternalFrameSize.width)/2,
    (desktopSize.height- jInternalFrameSize.height)/2);

Answer 2

Work out the top-left corner of the new location (based on the size of the JDesktopPane and JInternalFrame) and then call JInternalFrame.setLocation.

Answer 3

I would suggest the Window.setLocationRelativeTo(Component) method, which will center the window relative to a specified component. Instead of passing in a JDesktopPane, you might want to obtain the parent frame for a component, since otherwise, your JInternalFrame will be centered according to whichever component you pass in.

Here is a code sample:

private void showDialog(Dialog dialogToCenter, Component button) {
    Frame frame = JOptionPane.getFrameForComponent(button);
    dialogToCenter.setLocationRelativeTo(frame);
    dialogToCenter.setVisible(true);
}

Answer 4

If you are using Netbeans (which is recommended for desktop apps) you just need to:

1. Select the form, right click and then properties;
2. Go to code tab;
3. Change "Form size policy" from "Generate Pack()" to "Generate Resize Code";
4. Form Position (option above Form size policy) will be available.

Now you can set the for position as you wish :)