🚀 go-pugleaf

Beautifully explained!  My thanks once again!

Harry
"Torsten Welches" <torsten.welches@who.cares.netcologne.de> wrote in message
news:3ae51f20$1_1@dnews...
>
> Harry,
>
> the syntax is quite simple, just use the final keyword:
>
> final PrinterJob printerJob = PrinterJob.getPrinterJob();
>
> The reason is also quite simple once you fully understand what
> actually happens:
> Let me start by saying that this is not (only) about Threads
> but about inner classes. Your printthread is an inner class of
> your PrintButton_actionPerformed method.
> Now an instance of an inner class may well outlive your method
> invocation, your Thread being a good example for that - it will
> probably continue to run after your PrintButton_actionPerformed
> method has long returned.
> Normally a local variable (stack) will be automatically destroyed after
the method returns, because there is no way to
> access it anyway. As soon as local inner classes enter the
> picture this is no longer true. You Thread will probably use the
> printerJob instance sometimes after the method has already
> returned, so the normal local-variable-cleanup would be disastrous.
Marking the variable final is the way to tell the
> compiler that he has to preserve this very local variable
> even after the method has returned (on the heap).
>
> Make sense?
>
> Torsten
>
> "Harry Whitehouse" <harry@envmgr.com> wrote:
> >Well, I guess it's time to learn about the modifier "final"!
> >
> >I'm trying to spawn a thread for the printer dialog on my applet, so the
> >dialog has time to close on slower connections without blanking the
> >underlying applet GUI.  Heaven knows if my approach is even correct
(that's
> >another question <g>) but for now I need to understand about the compiler
> >error message indicated a local variable (in this case printerJob) needs
to
> >be declared final.  I've seen this in some other threads I've created (to
> >handle URL transactions), but have managed to sidestep this issue by
> >declaring and using non-local variables.
> >
> >First, what is the proper syntax for this?  I've tried some obvious
> >permutations but with no luck.
> >
> >And second, what is the significance of this modifier?
> >
> >
> > void PrintButton_actionPerformed(ActionEvent e) {
> >
> >        PrinterJob printerJob=null;
> >        bprintpostage=jCheckPrintPostage.isSelected();
> >        printerJob = PrinterJob.getPrinterJob();
> >
> >
> >       Thread printthread = new Thread() {
> >           public void run() {
> >              doPrint = printerJob.printDialog();
> >          }
> >        };
> >        printthread.start();
> >
> >        try {
> >            printthread.join();
> >        }
> >        catch (Exception jprintexp) {
> >            jprintexp.printStackTrace(System.out);
> >            return;
> >        }
> >
> >
> >TIA
> >
> >Harry
> >
> >
> >
>