Position a JPanel with code

[murrayja]

I am using NetBeans to convert an app from Visual Basic to Java. I have a JFrame on which I want to place two panels each taking half of the available JFrame space. I am using the absolute layout manager on the JFrame. When I run the app with one panel it refuses to occupy the left half of the JFrame space. here is my initialization code.....

public Titlebar() {
initComponents();
// -- set class to full screen --
Dimension d = java.awt.Toolkit.getDefaultToolkit().getScreenSize();
setLocation(0,0);
setSize(d.width, d.height);
// -- set panel to fill left half of frame --
pnlFields.setLocation(0,50);
pnlFields.setSize(d.width / 2, d.height - 50);
}

thanks
jim murray

 

[timw]

..so where exactly does it get drawn? Does it appear at all? What is happening in the initComponents() method? Have you added the pnlFields object to the Frame? For example (from memory, don't pick me up on incorrect signatures)...

frame.getContentPane.add(pnlFields, null);

Tim

 

[murrayja]

At design (NetBeans) I position the JPanel immediately below the menubar of the JFrame with W=H=500.

At run time it is in the same place, ie the width and height have not been changed to fill 1/2 the JFrame area.

InitComponents has this relating to the JPanel ...

pnlFields.setMinimumSize(new java.awt.Dimension(250, 250));
pnlFields.setPreferredSize(new java.awt.Dimension(500, 500));
getContentPane().add(pnlFields, new org.netbeans.lib.awtextra.AbsoluteConstraints(0, 0, 250, 320));

 

[timw]

Okay, try doing

this.getContentPane().validate();

at the end of your TitleBar constructor method.

Tim

 

[murrayja]

No Joy.

 

[timw]

Strange.. I knocked up a quick program using your code and it works fine. The difference I had is that I'm not using NetBeans, so when you set the layoutmanager for the frame, do

this.getContentPane().setLayoutManager(null);

and add the panel with

this.getContentPane().add(pnlFields, null)

Tim

 

[murrayja]

I had just tried setting the layout manager of the JFrame to null and it works ok now. I guess the lesson is to avoid a layout manager.
thanks
jim

 

[timw]

Well, you do get benefits from using one of the out-of-the-box Java LayoutManagers. See thread269-988099. The need to cling to null layouts is a hang-over from VB development IMO. LayoutManagers are more work but the results are worth it when developing application to run on machines with a variety of different screen resolutions.

Tim