Re: [returning error message on abort]how to interrupt normal process in a method

From:
Daniel Moyne <dmoyne@tiscali.fr>
Newsgroups:
comp.lang.java.help
Date:
Sat, 16 Dec 2006 17:29:25 +0100
Message-ID:
<em16t6$gem$1@news.tiscali.fr>
Andrew Thompson wrote:

Daniel Moyne wrote:

I have a method that return an array, something like this :

public String[] getAllClassName(Indi indi) {


/**
@throws ClassNameMissingException if no class names found
*/
public String[] getAllClassName(Indi indi)
    throws ClassNameMissingException {

        /* check for existing classes */

....

                                if (classname.equals("")) {
                                        /* here we want to abort */
                                        println("ERROR: empty _CLAS tag
                                        found for :"+indi); break; /* is
                                        this good */


    System.err.println(
        "ERROR: empty _CLAS tag found for :"+indi);
     throw new ClassNameMissingException();

                                        }
                                else {

....

}


class ClassNameMissingException extends Exception {
    ClassNameMissingException() {
    }
}

So when everything goes well I normally get an array of string values but
in some cases I want to abort the method and return an error message ; as
a method can just return an object (?) how to proceed neatly for the
caller of the method to get either :
- the array he wants,
- or possibly a notification of an error when aborting.


// the caller 'try's something that might fail..
try {
  String[] names = getAllClassName(Indi indi);
  // proceed with processing the class names
  // ....
} catch(ClassNameMissingException cnme) {
  //decide what to do here, usually a good thing is..
  cnme.printStackTrace();
}

With Java I am a little puzzled as the way to think is different.


Different to what? Another (OOP) language?
A procedural language?
Your understanding of Java at this moment?

Andrew T.

yes Andrew I was thinking of a produral language like Perl oa a Basic ; here
it is different more abstract.
Thanks for this great idea : I have to pull my sleeves up now !

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