Re: [returning error message on abort]how to interrupt normal process in a method
Lew wrote:
Daniel Moyne wrote:
public class ClassNameMissingException extends Exception {
public ClassNameMissingException(Indi indi,int errornumber) {
this.errornumber=errornumber;
this.indi=indi;
}
public int getErrorNumber() {
return errornumber;
}
public Indi getErrorIndi() {
return indi;
}
}
The class as shown does not contain instance variables "errornumber"
(should be spelled "errorNumber") or "indi". Hence you cannot in the
constructor use, for example,
this.indi=indi;
You need to add the instance variable:
private Indi indi;
What is class Indi? If it is a business-logic component it probably should
not be an Exception member, although there are justifications for some
lightweight objects. If it holds any resources (file handles, database
connections, ...) it must not be an Exception member.
Indi is a class defined for an Individual in Genealogy ; my app is a pluggin
of a existing Genealogy app where this Indi class is set.
Where do you want me to set this line :
private Indi indi;
Sometimes Exception classes do define additional elements, such as the
"SQLState" attribute of java.sql.SQLException. Note that "SQLState" is
lightweight and holds no resources.
You should re-define at least the default and String-argument Exception
constructors.
public ClassNameMissingException();
public ClassNameMissingException( String message );
Here I followed Andrew'logics to avort a method process by creating an
exception which is very clever but I need to collect information related to
my error.
You mean here that I have to replace the line :
public class ClassNameMissingException extends Exception {
by : this line :
public ClassNameMissingException( String message )....
If it is not possible to use the exception trick to transfer information to
the caller for him to process the error (software error used to detect
incoherency in a database) detected I will have to use something else.
lest inherited methods like "getMessage()" cause difficulty, and
define "void setIndi( Indi indi )" (assuming Indi is light enough)
and "void setErrorNumber( int en )".
(Error numbers are probably not very useful to track, since they introduce
a dependency on the external resource that maps such numbers to their
meanings. That is the trouble with "SQLState".)
You might find that you can encode everything you need in the message and
will have no need for extra attributes. An Exception should be nearly
atomic, almost immutable and quite independent.
- Lew