How to find JFrame border width?

Question

Hi, I need to find out the left & right border widths of a JFrame. This is easy if I have an existing object (assuming it's been painted at least once).
The border width may vary depending on the current look & feel, whether running on windows or the MAC, etc.
I want to find out this value without creating an instance of JFrame. So I thought I'd try the UIManager, and I thought I'd need something like this:
javax.swing.border.Border b = javax.swing.UIManager.getBorder("InternalFrame.border");But of course that's for InternalFrames, not JFrames.
I can't figure this out - any ideas?
Thanks, TL
PS. Plse don't ask why I need to know this width ;-)

Answer 1

So why do you need to know those widths?
sigh
Ok, like I said in my original post I really want to be able to do this. I'm disappointed that there's mostly questions 'why do you want to know' rather than workable solutions to the problem.
What say I wanted to have a console application to give me all these values, for the current platform and look & feel? Pretty ugly momentarily popping up a JFrame so I can get these widths.
But anyway here's the reason and I'm bracing for the inevitable 'you should not do that'.
I want to choose the size of some components to go on a panel (and if you draw it with some initial defaults and repaint immediately after the first draw, it looks pretty ugly).
We have a JList with a custom row renderer - each row has a number of columns in it, each to be defined as a percentage of the total width, so the renderer is a JPanel with all these things on it. (For several reasons a JTable was not appropriate, not the least of which the data needs to be displayed and manipulated as a list... although the underlying data IS in a TableModel.)
I literally spent days trying to make the custom row renderer work as we needed it, using standard layouts - tried gridbaglayouts, but this doesn't support percentage widths (the weighting factors are a hindrance if there's no text in one column but lots in another, etc); other layout managers such as a box layout nicely give me a number of columns, but they are all equally spaced (no good if you want one to be 10% of the total width, and the next to be 50%...). And so the issues go on with the other standard layouts.
Anyway, none of the standard java layout managers would do what we wanted and I didn't find one on the 'net to fit the job (at least not one under LGPL) - unless I missed one. So we resorted to absolute positioning. This works perfectly, and we also listen for window resize events - that works very well also. The trouble is, when INITIALLY sizing a column, we need to make it a percentage of the width. What is the 'useable width'? When we initially construct the window we know how big we're making the it, and if the frame is maximised then that's easy, the left & right borders are zero width. However that's under XP and with the current look & feel, so it isn't guaranteed. Similarly it the initial window size is not full-screen, there are most likely some borders, so how wide are they?
Right, the best suggestion so far is for the use of pack(). We generally don't need to do this as we have a set of core frame classes which manage their sizes (and do it consistently throughout the application), and don't use pack(). However in this case, calling pack() before adding all the components of the JPanel will populate the border widths if applicable. However some changes I've just made to accomodate some MAC quirks means that a resize event occurs on startup anyway, and this seems to have largely solved the problem.
However, I'd still like to know the answer to my original question. And I thought the answer may lie in asking the UIManager, but haven't found a setting in there for this purpose...