Re: Eclipse - NoSuchMethodError: main

From:
Lew <noone@lewscanon.com>
Newsgroups:
comp.lang.java.programmer
Date:
Fri, 23 Mar 2012 07:51:46 -0700
Message-ID:
<jki2m2$uj3$1@news.albasani.net>
On 03/23/2012 06:36 AM, William Colls wrote:

On 03/21/2012 08:46 PM, Eric Sosman wrote:

On 3/21/2012 10:17 AM, William Colls wrote:

I think this is really an Eclipse problem.

When I try to run my program, I get the error message

NoSuchMethodFound: main

The file does in fact contain a main method, declared as public static
void, with no arguments.

I suspect that Eclipse is looking in the wrong place for the method, but
in every place that I can find in the various configurations, the file
that I am running is identified as the file containing containing the
main() method.

Any suggestions as to where further to look will greatfully received.


Others have explained that "main" must have a parameter list
consisting of exactly one String array. For completeness' sake,
it's *possible* to have a "main" with some other signature; as with
any other method, you can overload "main" as you wish:

public static void main(String[] args) { ... }
public static int main() { return 42; }
public static double main(String justOneArg) {
return Double.parseDouble(justOneArg);
}
...

However, the particular "main" that Java (not just Eclipse) looks
for when starting execution is the one and only "main" that has the
first form above. (You can write "String... args" instead of
"String[] args" if you like, but it's the same thing. Java starts
with the "main" whose parameter list is one String array, however
you happen to express it.)

Only the type of the formal parameter matters; the actual name
is irrelevant. When the arguments aren't used, my own personal
practice is to write

public static void main(String[] unused) { ... }

The only drawback is that code-policing tools sometimes insist
that I write Javadoc comments for the "unused" parameter ;-)


Thanks to all who replied. I changed the the signature to

public static void(String[] args)

but it made no difference - same problem.


That would fail to compile.

Please prepare an SSCCE for us.
http://sscce.org/

I made the assumption that it was/is an Eclipse configuration issue, based on
the fact that When I first started with Java, I was using the Netbeans IDE,
and the main() worked perfectly well there, but I would get the
NoSuchMethodError if project setup page didn't point to the correct file.


What happens when you invoke it via "java" on the command line?

I have side-stepped the problem by creating a small class that does have a
main method, imports the class I have defined and am building, and then


This makes no sense at all. Something there is you have not told us, mmm.

instansiates an object form it, and invokes the methods I need to test. Better
solution, as it more closely the real world use of the work I am doing.


--
Lew
Honi soit qui mal y pense.
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