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Compile Problem involving Dependencies

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  Compile Problem involving Dependencies Novice <novice@example..com> - 2011-10-29 17:06 +0000
    Re: Compile Problem involving Dependencies markspace <-@.> - 2011-10-29 10:18 -0700
      Re: Compile Problem involving Dependencies Novice <novice@example..com> - 2011-10-29 17:29 +0000
        Re: Compile Problem involving Dependencies markspace <-@.> - 2011-10-29 12:32 -0700
          Re: Compile Problem involving Dependencies Lew <lewbloch@gmail.com> - 2011-10-29 17:06 -0700
            Re: Compile Problem involving Dependencies Roedy Green <see_website@mindprod.com.invalid> - 2011-10-30 01:28 -0700
    Re: Compile Problem involving Dependencies Martin Gregorie <martin@address-in-sig.invalid> - 2011-10-29 17:24 +0000
    Re: Compile Problem involving Dependencies Roedy Green <see_website@mindprod.com.invalid> - 2011-10-29 23:25 -0700

#9298 — Compile Problem involving Dependencies

I'm having a problem compiling some Java code which I _think_ has to do 
with a dependency issue that I don't fully understand. I wonder if someone 
here can enlighten me?

I have a class named FooApplet which is defined as public and extends 
JApplet. FooApplet makes use of a class I wrote called WrapUtils, which is 
simply a public class. WrapUtils in turn makes use of other classes I wrote 
called ErrorUtils and CountUtils, both of which are simply public classes. 

I'm using Eclipse 3.7 and FooApplet compiles just fine. However, WrapUtils 
shows compile errors at every mention of ErrorUtils and CountUtils. 
ErrorUtils and CountUtils both compile cleanly. 

The suggested fixes for the errors in WrapUtils include generating an 
import statement for ErrorUtils and CountUtils, even though they are in the 
same package as WrapUtils. When I click on the option to generate those 
imports, the import statement is NOT added to WrapUtils and the errors for 
ErrorUtils and CountUtils remain. The red "x" remains on WrapUtils both in 
the editor and in Package Explorer. Why does Eclipse not see the ErrorUtils 
and CountUtils? All of the classes are public and all of WrapUtils, 
CountUtils and ErrorUtils are in the same package, although it is a 
different package than the one containing FooApplet?

So, to recap, we have:

com.foo.FooApplet (public extends JApplet)
  - invokes com.foo.utilities.WrapUtils (public) 
    - invokes com.foo.utilities.CountUtils (public)
    - invokes com.foo.utilities.ErrorUtils (public)

All references to CountUtils and ErrorUtils in WrapUtils are flagged as 
compile errors: "CountUtils cannot be resolved".

What stupid mistake am I making? Is this a dependency error? Or is the fact 
that the methods in WrapUtils, CountUtils and ErrorUtils are all static 
that are the source of the problem?

-- 
Novice

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#9299

On 10/29/2011 10:06 AM, Novice wrote:
> com.foo.FooApplet (public extends JApplet)
>    - invokes com.foo.utilities.WrapUtils (public)
>      - invokes com.foo.utilities.CountUtils (public)
>      - invokes com.foo.utilities.ErrorUtils (public)


This should work, although you have shown any code and don't say how you 
"invoke" a class.  It's possible that Eclipse is just confused.  Try 
clean and rebuild, saving all files, checking the file system directly 
to make sure it actually matches what you think you are seeing, and 
double checking project properties.  Don't forget the old "reboot and 
see if it works."

Could be a problem with how you are invoking the classes however, or how 
you've included other projects or libraries.  Best to supply a 
compilable example that duplicates the problem if you want the most help.

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#9302

markspace <-@.> wrote in news:j8hch3$atn$1@dont-email.me:

> On 10/29/2011 10:06 AM, Novice wrote:
>> com.foo.FooApplet (public extends JApplet)
>>    - invokes com.foo.utilities.WrapUtils (public)
>>      - invokes com.foo.utilities.CountUtils (public)
>>      - invokes com.foo.utilities.ErrorUtils (public)
> 
> 
> This should work, although you have shown any code and don't say how you 
> "invoke" a class.  It's possible that Eclipse is just confused.  Try 
> clean and rebuild, saving all files, checking the file system directly 
> to make sure it actually matches what you think you are seeing, and 
> double checking project properties.  Don't forget the old "reboot and 
> see if it works."
> 
> Could be a problem with how you are invoking the classes however, or how 
> you've included other projects or libraries.  Best to supply a 
> compilable example that duplicates the problem if you want the most help.
> 
> 

Many thanks, markspace! The fresh build did the trick; all the compiler 
errors went away and I was able to run the applet successfully. I like 
Eclipse but it does seem to get confused sometimes; I should have thought 
of the rebuild as a possible solution.

I would have gone to a code example if no one could suggest a solution 
without one but you've saved me the bother ;-)

Thanks again!

-- 
Novice

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#9306

On 10/29/2011 10:29 AM, Novice wrote:
>  The fresh build did the trick; all the compiler
> errors went away and I was able to run the applet successfully. I like
> Eclipse but it does seem to get confused sometimes; >


You're welcome.  NetBeans seems to have the same problem.  Periodically 
weird errors show up and I have to do the "clean and rebuild full 
project."  I guess it might be common behavior related to some compiler 
API they both use, since Java has made one available for programmers a 
while back.

*shrug*  At least you didn't have to reach for the "big red switch."

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#9307

markspace wrote:
> Novice wrote:
>>  The fresh build did the trick; all the compiler
>> errors went away and I was able to run the applet successfully. I like
>> Eclipse but it does seem to get confused sometimes; >
> 
> You're welcome.  NetBeans seems to have the same problem.  Periodically 

Pretty much *all* build systems have this problem.

> weird errors show up and I have to do the "clean and rebuild full 
> project."  I guess it might be common behavior related to some compiler 
> API they both use, since Java has made one available for programmers a 
> while back.
> 
> *shrug*  At least you didn't have to reach for the "big red switch."

It's common behavior to all build systems, particularly Java-esque ones that track dependencies through the .class files in the "-d" target directory of javac.

In the face of refactoring and certain strange scenarios, .class files remain in the target directory for which either the source files have a changed transitive dependency or the source no longer exists or a constant is not deemed worthy of a recompile or what-all.

Later another class sees something in the now-no-longer-valid .class file and weirdness ensues.  Finally the hapless programmer does a full "clean", and voilà! Problem solved.

-- 
Lew

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#9311

On Sat, 29 Oct 2011 17:06:43 -0700 (PDT), Lew <lewbloch@gmail.com>
wrote, quoted or indirectly quoted someone who said :

>Pretty much *all* build systems have this problem.

IntelliJ seems to keep very good track. When I export and compile with
ANT, a  clean build will help, especially getting rid of obsolete
class files (e.g. for inner classes).
-- 
Roedy Green Canadian Mind Products
http://mindprod.com
It's difficult to be rigorous about whether a machine really knows,
thinks, etc., because we’re hard put to define these things. 
We understand human mental processes only slightly better than
a fish understands swimming. 
~ John McCarthy (born: 1927-09-04 died: 2011-10-23 at age: 84).
Inventor of the term AI (Artificial Intelligence), 
the short-circuit OR operator (|| in Java), 
and LISP (LIst Processing Language) that makes EMACS 
(Extensible MACro System) so addictive.

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#9301

On Sat, 29 Oct 2011 17:06:46 +0000, Novice wrote:

> I'm having a problem compiling some Java code which I _think_ has to do
> with a dependency issue that I don't fully understand. I wonder if
> someone here can enlighten me?
> 
> I have a class named FooApplet which is defined as public and extends
> JApplet. FooApplet makes use of a class I wrote called WrapUtils, which
> is simply a public class. WrapUtils in turn makes use of other classes I
> wrote called ErrorUtils and CountUtils, both of which are simply public
> classes.
> 
> I'm using Eclipse 3.7 and FooApplet compiles just fine. However,
> WrapUtils shows compile errors at every mention of ErrorUtils and
> CountUtils. ErrorUtils and CountUtils both compile cleanly.
> 
> The suggested fixes for the errors in WrapUtils include generating an
> import statement for ErrorUtils and CountUtils, even though they are in
> the same package as WrapUtils. When I click on the option to generate
> those imports, the import statement is NOT added to WrapUtils and the
> errors for ErrorUtils and CountUtils remain. The red "x" remains on
> WrapUtils both in the editor and in Package Explorer. Why does Eclipse
> not see the ErrorUtils and CountUtils? All of the classes are public and
> all of WrapUtils, CountUtils and ErrorUtils are in the same package,
> although it is a different package than the one containing FooApplet?
> 
> So, to recap, we have:
> 
> com.foo.FooApplet (public extends JApplet)
>   - invokes com.foo.utilities.WrapUtils (public)
>     - invokes com.foo.utilities.CountUtils (public)
>     - invokes com.foo.utilities.ErrorUtils (public)
> 
> All references to CountUtils and ErrorUtils in WrapUtils are flagged as
> compile errors: "CountUtils cannot be resolved".
> 
> What stupid mistake am I making? Is this a dependency error? Or is the
> fact that the methods in WrapUtils, CountUtils and ErrorUtils are all
> static that are the source of the problem?

You don't mention where the classes are in your directory structure or 
the package name of FooApplet. I would assume that, relative to where 
Eclipse is run you'd find that

- FooApplet contains the "package com.foo;" declaration

- all three other sources contain the "package com.foo.utilities;"
  declaration.

- the path names of the .java files relative to the Eclipse root are:

  com/foo/FooApplet.java
  com/foo/utilities/WrapUtils.java 
  com/foo/utilities/CountUtils.java 
  com/foo/utilities/WrapUtils.java 

If your package declarations and relative pathnames differ, thats most 
likely the cause.
 

-- 
martin@   | Martin Gregorie
gregorie. | Essex, UK
org       |

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#9309

On Sat, 29 Oct 2011 17:06:46 +0000 (UTC), Novice <novice@example..com>
wrote, quoted or indirectly quoted someone who said :

>
>I'm having a problem compiling some Java code which I _think_ has to do 
>with a dependency issue it.

The easy way to handle dependency problems to compile everything at
once and let Javac sort it out. You can do this with *.java on the
javac command line or using ANT.  

See http://mindprod.com/jgloss/javac.exe
http://mindprod.com/jgloss/ant.html

I have a feeling you also need to read
http://mindprod.com/jgloss/classpath.html
and 
http://mindprod.com/jgloss/package.html
-- 
Roedy Green Canadian Mind Products
http://mindprod.com
It's difficult to be rigorous about whether a machine really knows,
thinks, etc., because we’re hard put to define these things. 
We understand human mental processes only slightly better than
a fish understands swimming. 
~ John McCarthy (born: 1927-09-04 died: 2011-10-23 at age: 84).
Inventor of the term AI (Artificial Intelligence), 
the short-circuit OR operator (|| in Java), 
and LISP (LIst Processing Language) that makes EMACS 
(Extensible MACro System) so addictive.

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