Re: Some same exceptions used in a given file
On 04/23/2011 06:00 PM, Merciadri Luca wrote:
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Eric Sosman<esosman@ieee-dot-org.invalid> writes:
On 4/23/2011 1:08 PM, Merciadri Luca wrote:
In some of my code files, I've got the following catch block
==
catch (IOException cantOpenFile)
{
System.err.println("Can't open " + inputFilename + ".");
System.exit(1);
}
==
more than once, but at different places in the file. Is it possible to
define this somewhere so that I can directly catch the exception with
the two given commands? (Just as one would define his own exception.)
Could you give an example of what you're trying to do? (The
above isn't sufficiently informative.)
Thanks for the answers. Sure I can provide more details. Let us
consider the following constructor:
==
public FileStream ()
{
try
{
outputFile = new BufferedWriter(new FileWriter("hello.txt"));
}
catch (IOException cantWriteInFile)
{
System.out.println("Impossible to write (in) hello.txt.");
System.exit(1);
}
}
==
You saw that I had to catch an IOException, as expected when dealing
with a BufferedWriter.
Now, in a function of the same class of the constructor (class
FileStream), I need to write in the output file. As a result, I've got
==
public void write (String outputText)
{
try
{
outputFile.write(outputText);
outputFile.close();
}
catch (IOException cantWriteInFile)
{
System.out.println("Impossible to write (in) hello.txt.");
System.exit(1);
}
}
==
You directly notice that the two catch blocks are identical. As a
result, I'd like to do something like this (in pseudocode):
==
public FileStream ()
{
try
{
outputFile = new BufferedWriter(new FileWriter("hello.txt"));
}
catch (IOException cantWriteInFile);
}
==
then, later in the file:
==
public void write (String outputText)
{
try
{
outputFile.write(outputText);
outputFile.close();
}
catch (IOException cantWriteInFile);
}
==
where IOException cantWriteInFile is defined in the class as
==
System.out.println("Impossible to write (in) hello.txt.");
System.exit(1);
==
Is there a way to do this? It looks terribly bad to have the same
catch code in two different methods.
Not really, and not at all in the fashion you're requesting.
You do NOT want to put 'System.exit()' in a 'catch' block. I thought we'd
made that clear already. Do you attend to the answers we give you? I wish
you would, please.
You especially don't want to call 'System.exit()' from within a constructor.
Pay attention, now.
Some people try putting a "common" method in the 'catch' block that logs,
closes and exits, but that's a TERRIBLE practice. Among other things, it
defeats the compiler's analysis of "definitely (un)assigned".
The problem is that these are different 'IOException's, that is, they have to
be caught at wildly different times.
As another respondent indicated in another thread, you can do things like what
you're asking with aspect-oriented programming (AOP). Sometimes when you
think about the answers you've been given you can find answers to questions
you hadn't considered earlier. It pays HUGE dividends to ponder each answer,
googling for unfamiliar terms and supplementing with your own effort at
research and review of materials proffered.
If you don't revuew the advice, why ask for it?
--
Lew
Honi soit qui mal y pense.
http://upload.wikimedia.org/wikipedia/commons/c/cf/Friz.jpg