The basic setup is this: I have a vertical JSplitPane that I want to have a fixed-size bottom component and a resizing top component, which I accomplished by calling setResizeWeight(1.0). In this application there is a button to restore the "default" window configuration. The default height of the window is the desktop height, and the default divider location is 100 pixels from the bottom of the split pane.
To set the divider location to 100px, I take the JSplitPane height - 100. The problem is, just before this I resize the JFrame, and since the code is in a button callback, the JSplitPane has been invalidated but not yet resized. So the divider location is set incorrectly.
Here is a SSCCE. Click the button twice to see the problem. The first click will resize the window, but the divider location remains the same (relative to the bottom of the window). The second click properly moves the divider, since the window size didn't change.
import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.GraphicsConfiguration;
import java.awt.Insets;
import java.awt.Rectangle;
import java.awt.Toolkit;
import java.awt.event.ActionEvent;
import javax.swing.AbstractAction;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JSplitPane;
public class SSCCE {
/**
* @param args unused
*/
public static void main(String[] args) {
new SSCCE();
}
private final JFrame f = new JFrame("JSplitPane SSCE");
private final JSplitPane sp = new JSplitPane(JSplitPane.VERTICAL_SPLIT,true);
public SSCCE() {
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
sp.add(new JLabel("top"));
sp.add(new JLabel("bottom"));
sp.setResizeWeight(1.0);
f.getContentPane().add(sp);
f.getContentPane().add(new JButton(new AbstractAction("Resize to Default") {
@Override
public void actionPerformed(ActionEvent e) {
restoreDefaults();
}
}),BorderLayout.PAGE_END);
f.setSize(400,300);
f.setVisible(true);
}
void restoreDefaults() {
f.setSize(f.getWidth(), getDesktopRect(f.getGraphicsConfiguration()).height);
sp.setDividerLocation(sp.getSize().height - 100); // Does not work on first button press
}
Rectangle getDesktopRect(GraphicsConfiguration gc) {
Toolkit toolkit = Toolkit.getDefaultToolkit();
Dimension size = toolkit.getScreenSize();
Insets insets = toolkit.getScreenInsets(gc);
return new Rectangle(insets.left, insets.top, size.width - (insets.left + insets.right), size.height - (insets.top + insets.bottom));
}
}
I have thought of a few ways I might get around this, but they all seem sort of hackish. So far the best idea I've had has been to call f.validate() in between setting the frame size and setting the divider location, but I'm concerned there might be side effects to forcing validation early.
The other option I thought of is to use EventQueue.invokeLater() to put the call to set the divider location at the end of the event queue. But that seems risky to me - I'm assuming the JSplitPane will have been validated at that point, and I'm concerned that may be a faulty assumption to make.
Is there a better way?
