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

From:
"Andrew Thompson" <andrewthommo@gmail.com>
Newsgroups:
comp.lang.java.help
Date:
16 Dec 2006 07:33:58 -0800
Message-ID:
<1166283238.562072.288350@l12g2000cwl.googlegroups.com>
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.

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