Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > comp.lang.java.programmer > #13097 > unrolled thread

Eclipse - NoSuchMethodError: main

Back to article view | Back to comp.lang.java.programmer

Contents

  Eclipse - NoSuchMethodError: main William Colls <william.colls@rogers.com> - 2012-03-21 10:17 -0400
    Re: Eclipse - NoSuchMethodError: main Jussi Piitulainen <jpiitula@ling.helsinki.fi> - 2012-03-21 16:41 +0200
    Re: Eclipse - NoSuchMethodError: main markspace <-@.> - 2012-03-21 08:18 -0700
    Re: Eclipse - NoSuchMethodError: main Lew <lewbloch@gmail.com> - 2012-03-21 13:41 -0700
    Re: Eclipse - NoSuchMethodError: main Eric Sosman <esosman@ieee-dot-org.invalid> - 2012-03-21 20:46 -0400
      Re: Eclipse - NoSuchMethodError: main Arne Vajhøj <arne@vajhoej.dk> - 2012-03-21 21:00 -0400
        Re: Eclipse - NoSuchMethodError: main BGB <cr88192@hotmail.com> - 2012-03-21 21:59 -0700
          Re: Eclipse - NoSuchMethodError: main Patricia Shanahan <pats@acm.org> - 2012-03-22 03:13 -0700
            Re: Eclipse - NoSuchMethodError: main Arne Vajhøj <arne@vajhoej.dk> - 2012-03-22 21:46 -0400
              Re: Eclipse - NoSuchMethodError: main Lew <lewbloch@gmail.com> - 2012-03-22 18:49 -0700
                Re: Eclipse - NoSuchMethodError: main Gene Wirchenko <genew@ocis.net> - 2012-03-22 22:17 -0700
      Re: Eclipse - NoSuchMethodError: main William Colls <william.colls@rogers.com> - 2012-03-23 09:36 -0400
        Re: Eclipse - NoSuchMethodError: main Lew <noone@lewscanon.com> - 2012-03-23 07:51 -0700
          Re: Eclipse - NoSuchMethodError: main Patricia Shanahan <pats@acm.org> - 2012-03-23 08:49 -0700
    Re: Eclipse - NoSuchMethodError: main Jan Burse <janburse@fastmail.fm> - 2012-03-23 18:05 +0100

#13097 — Eclipse - NoSuchMethodError: main

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.

Thanks for your time.

William.

[toc] | [next] | [standalone]

#13098

William Colls writes:

> 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.

Have you tried declaring it correctly?

Either:   public static void main(String[] args)
or:       public static void main(String... args).

<http://docs.oracle.com/javase/specs/jls/se7/html/jls-12.html#jls-12.1.4>

[toc] | [prev] | [next] | [standalone]

#13100

On 3/21/2012 7:17 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.


No arguments?  In Java, the signature must match exactly.  The argument 
declaration is required.

[toc] | [prev] | [next] | [standalone]

#13110

William Colls wrote:
> I think this is really an Eclipse problem.

Nope.

> 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.

It's a programmer problem.

> 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 [sic] received.
 
Jussi and markspace explained the problem.

I will generalize the answer for you:

Do not suspect Eclipse first. Do not suspect Java first. Always suspect the programmer first.

-- 
Lew

[toc] | [prev] | [next] | [standalone]

#13113

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 ;-)

-- 
Eric Sosman
esosman@ieee-dot-org.invalid

[toc] | [prev] | [next] | [standalone]

#13115

On 3/21/2012 8:46 PM, Eric Sosman wrote:
> 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 ;-)

That could be considered a good opportunity to put in some
funny comments!

Arne

[toc] | [prev] | [next] | [standalone]

#13119

On 3/21/2012 6:00 PM, Arne Vajhøj wrote:
> On 3/21/2012 8:46 PM, Eric Sosman wrote:
>> 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 ;-)
>
> That could be considered a good opportunity to put in some
> funny comments!
>

yep, and maybe go into some long rant about something almost entirely 
irrelevant (hmm... sadly not too far from the truth sometimes...).

[toc] | [prev] | [next] | [standalone]

#13121

BGB wrote:
> On 3/21/2012 6:00 PM, Arne Vajhøj wrote:
>> On 3/21/2012 8:46 PM, Eric Sosman wrote:
>>> 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 ;-)
>>
>> That could be considered a good opportunity to put in some
>> funny comments!
>>
> 
> yep, and maybe go into some long rant about something almost entirely 
> irrelevant (hmm... sadly not too far from the truth sometimes...).

How about "This comment is intentionally left empty."?

Patricia

[toc] | [prev] | [next] | [standalone]

#13126

On 3/22/2012 6:13 AM, Patricia Shanahan wrote:
> BGB wrote:
>> On 3/21/2012 6:00 PM, Arne Vajhøj wrote:
>>> On 3/21/2012 8:46 PM, Eric Sosman wrote:
>>>> 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 ;-)
>>>
>>> That could be considered a good opportunity to put in some
>>> funny comments!
>>>
>>
>> yep, and maybe go into some long rant about something almost entirely
>> irrelevant (hmm... sadly not too far from the truth sometimes...).
>
> How about "This comment is intentionally left empty."?

@param unused What do you think?
@param unused To be used or not to be used that is the question!

:-)

Arne

[toc] | [prev] | [next] | [standalone]

#13127

Arne Vajhøj wrote:
> @param unused What do you think?
> @param unused To be used or not to be used that is the question!
> 
> :-)

* @param unused as I am to public speaking, I stand before you ...

-- 
Lew

[toc] | [prev] | [next] | [standalone]

#13129

On Thu, 22 Mar 2012 18:49:42 -0700 (PDT), Lew <lewbloch@gmail.com>
wrote:

>Arne Vajhøj wrote:
>> @param unused What do you think?
>> @param unused To be used or not to be used that is the question!
>> 
>> :-)
>
>* @param unused as I am to public speaking, I stand before you ...

     You need The Commentator:
          http://www.cenqua.com/commentator/

Sincerely,

Gene Wirchenko

[toc] | [prev] | [next] | [standalone]

#13132

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.

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.

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 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.

Again thanks to all for your helpful responses.

William.

[toc] | [prev] | [next] | [standalone]

#13133

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.
http://upload.wikimedia.org/wikipedia/commons/c/cf/Friz.jpg

[toc] | [prev] | [next] | [standalone]

#13134

On 3/23/2012 7:51 AM, Lew wrote:
> On 03/23/2012 06:36 AM, William Colls wrote:
...
>> 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/

It may be a package issue.

Patricia

[toc] | [prev] | [next] | [standalone]

#13135

There is a difference between:

     NoSuchMethodException     (1)

And

     NoSuchMethodError         (2)

If you get (1) then all your classes could load,
but the method in question does not exist. If
you get (2) then a problem existed during the
load of your classes in the first place.

The difference is indicated by the different
super class chain of the two exceptions:

     NoSuchMethodException     (1)
     ReflectiveOperationException
     Exception

And


     NoSuchMethodError         (2)
     IncompatibleClassChangeError
     LinkageError
     Error

I observed that the XXXErrors can easily happend
when incompatible versions of compiled .jars are
mixed. For example I had the case, compiled
B against A.jar:

    class A;            in     A.jar

    class B extends A;  in     B.jar

Now had a different version of A, call it A2.jar

    final class A;      in     A2.jar

When I tried to run A2.jar+B.jar one gets typically
a linkage error, since A is suddently final and
not supposed to be extended. Similar things can
happend with other expectations inside a class
that cannot be resolved at runtime.

Bye


William Colls schrieb:
> 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.
>
> Thanks for your time.
>
> William.

[toc] | [prev] | [standalone]

Back to top | Article view | comp.lang.java.programmer

csiph-web