HELP! Eclipse failing to build after returning to 1.4

Posted on 2006-07-24
Last Modified: 2010-08-05
Dear Experts,

HELP!  I'm in the middle of converting my Eclipse app from 1.4 to 5. Previously, I had been able to go to Java Compiler, and swap the "compiler compliance level" from 1.4 to 5, and BACK, and it worked fine.  Now, it SAYS it's doing a build, but it's not producing any classes when I swap back to 1.4.  (And it's taking one second, instead of the usual five seconds.)

In the Package Explorer window, my project DOES show a red "x", but none of the source files is similarly marked.  I have checked that my libraries are all there, and they are.  I have deleted all the classes, and tried to rebuild, but no luck.  And I have tried making trivial changes to code, in case the compiler felt nothing had changed, but no luck there, either.


Question by:BrianMc1958
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LVL 14

Expert Comment

ID: 17168360
Recreate a project using the old source files, but first copy the source to some safe place
LVL 86

Expert Comment

ID: 17168392
make sure you haven't removed it from the build path
LVL 30

Accepted Solution

Mayank S earned 500 total points
ID: 17168416
Goto Window -> Show View -> Problems log to see what the errors are in the first place.
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Author Comment

ID: 17168515
The build path seems OK, although it does still reference the jre1.5...  The "Problems" log doesn't show any errors within this particular project.  I haven't tried recreating the project with old source yet, because that makes me scared and I'm not quite that desperate yet.  (I'm still a bit of a newbie at Eclipse...)
LVL 30

Expert Comment

by:Mayank S
ID: 17168540
>> The build path seems OK, although it does still reference the jre1.5...

It should reference 1.4 if that is what you want. Right-click on the project, goto Properties -> Java Build Path -> Libaries tab -> remove the JRE 5 library and click on Add Library -> JRE System library, then select the 1.4 one.
LVL 30

Expert Comment

by:Mayank S
ID: 17168578
>> I haven't tried recreating the project with old source yet, because that makes me scared and I'm not quite that desperate yet.

It should work with the existing project. Just make sure you back-up the source-code files in some directory, just in case ;-)

Author Comment

ID: 17168584
At this point, it won't re-build even when I switch back to 5.0.  (I did not have to manually change the JRE library previously.  I just set the "compiler compliance level.")
LVL 86

Expert Comment

ID: 17168608
Do your other projects build?

Author Comment

ID: 17168705
Um, no.  Nothing buids now.  What have I done?

Author Comment

ID: 17168890
Sorry to have wasted your time again, folks.  It seems Windows got confused about a lock on my output classes directory.

For anyone reading this, I'm accepting mayankeagle's response here because it was close (and I didn't know about it before!)  In my case, though, I needed not "Problems" but "Error Log".  Apparently, if the build itself fails to run, that's where it dumps the message.

Thanks again, everybody...

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