Error in actionPerformed???

Re: Error in actionPerformed ???

"Geoff" <geoff104@hotma il.com> wrote in message
news:18143a5b.0 403030230.3762e [email protected] gle.com...[color=blue]
> Hey, I'm trying to design a simple interface and I'm getting this
> error:
>
> actionPerformed (java.awt.event .ActionEvent) in GUI cannot implement
> actionPerformed (java.awt.event .ActionEvent) in
> java.awt.event. ActionListener; overridden method does not throw
> java.io.IOExcep tion
> public void actionPerformed (ActionEvent event)
>
> I'm sure this is fairly simple but i'm relatively new to java and
> can't work it out!
>
> The code for actionPerformed is as follows, where GetContent and
> CompareFiles are outside classes which deal with the URL and GUI is
> the name of the overall class...
>
> -----------------------------
>
> public void actionPerformed (ActionEvent event)
> throws MalformedURLExc eption, IOException {[/color]
*snip code*

The problem is exactly what it says. You can't make a method throw an
exception that doesn't. The actionPerformed method isn't declared to throw
an IOException, therefore you can't try to make it do so. However, at no
time in your code do you throw an IOException anyway. You catch any that
occur, so your method doesn't *need* this declaration, unless you're
planning to change it. I think you need to read up a bit more on Exceptions.
MalformedURLExc eption is a RuntimeExceptio n, which is treated a bit
differently and probably won't cause you this problem, but again, you don't
need it there.

Re: Error in actionPerformed ???

geoff104@hotmai l.com (Geoff) wrote in message news:<18143a5b. 0403030230.3762 [email protected] ogle.com>...[color=blue]
> Hey, I'm trying to design a simple interface and I'm getting this
> error:
>
> actionPerformed (java.awt.event .ActionEvent) in GUI cannot implement
> actionPerformed (java.awt.event .ActionEvent) in
> java.awt.event. ActionListener; overridden method does not throw
> java.io.IOExcep tion
> public void actionPerformed (ActionEvent event)
>
> I'm sure this is fairly simple but i'm relatively new to java and
> can't work it out!
>
> The code for actionPerformed is as follows, where GetContent and
> CompareFiles are outside classes which deal with the URL and GUI is
> the name of the overall class...
>
> -----------------------------
>
> public void actionPerformed (ActionEvent event)
> throws MalformedURLExc eption, IOException {
>
> try {
> URL url = new URL(enterURL.ge tText());
> URLConnection connection = url.openConnect ion();
> GetContent gc = new GetContent();
> CompareFiles cf = new CompareFiles();
> }
>
> catch (MalformedURLEx ception err)
> {
> System.err.prin tln("Usage: java URLApp
> http://www.URL.com");
> }
> catch (IOException e)
> {
> System.err.prin tln("Run software again to check if
> content has changed.");
> }
>
> -----------------------------
>
> Thanks a lot,
> Geoff[/color]


You method does not actually throw those errors. It catches and
handles them. Remove the throws from your method signature.

Greg

Re: Error in actionPerformed ???

Yea I'd fixed the error but wasn't sure how.. but i know now, cheers!

Re: Error in actionPerformed ???

geoff104@hotmai l.com (Geoff) wrote in message news:<18143a5b. 0403030230.3762 [email protected] ogle.com>...[color=blue]
> Hey, I'm trying to design a simple interface and I'm getting this
> error:
>
> actionPerformed (java.awt.event .ActionEvent) in GUI cannot implement
> actionPerformed (java.awt.event .ActionEvent) in
> java.awt.event. ActionListener; overridden method does not throw
> java.io.IOExcep tion
> public void actionPerformed (ActionEvent event)
>
> I'm sure this is fairly simple but i'm relatively new to java and
> can't work it out![/color]

As correctly noted elsewhere, it isn't possible for the exceptions listed
in the 'throws' clause to actually _escape_ from the method, due to the
exception handlers wrapping the main body of the code.

One unrelated, but useful, point: it really isn't good practice to run
lengthy operations - especially network IO where timings are particularly
unpredictable - from within an event handler. Event methods are called
on someone else's thread, so long execution times hog that thread and
prevent it from doing anything else (like processing further events,
perhaps!) Best practice is to exit from an event handler ASAP - firing
off a separate thread of our own if extended processing time is required.


-FISH- ><>