1. Ensure that the project->build automatically has been selected.
2. If selected, also does not work, use this recruit: Project->clean. -> Select 2nd Clean Select project, hook up start build immediatelly
3. Delete the current project, set up the compile file output path in advance, re-import the source file, set Eclipse to compile when saving, and then compile it automatically when you save it.
4. If the project leads to some unused jar bag, and the bag is deleted by you, there will be no error, but how can not compile the class file situation, you can remove all the packages, and then one after the introduction (need), not all of a sudden put all the bags are introduced, useless may cause undesirable consequences.
5. Want to delete a class file regeneration, remove the class file, but the Classes directory folder is opened by other programs, such as Total commander. At this point, the compilation will not pass, under problems may prompt "con" t delete classes ... ". Turn off other programs and recompile.
6. There is also the case that the JRE System Library is removed and can be compiled by re-import. But what causes it is not clear.
7. Remove all the packages from the build path. Then add Jars,add libraries the need to add in, incredibly began to compile ...
8.project->properties->java Build PATH->SOURCE->.../WEB-INF/SRC output folder do not default, edit let it point to ... /web-inf/classes
Then click the Build project again to automatically compile.
Individuals use this to solve the problem
9. Then the most important to see whether the project below the work directory, because the CVS control does not add work version, so checkout after this directory, to hand-add some of the project can be automatically compiled
