MyEclipse cannot automatically compile the solution (reproduced)

MyEclipse cannot automatically compile the solution (reproduced)
MyEclipse does not compile the solution 1. Make sure that project->build automatically has been selected. MyEclipse does not compile the solution 2. If it is selected, it is not easy to use, use this trick: project-> clean..->Select the second clean select project, check start build immediately,

MyEclipse does not compile to solve 3. Delete the current project, set the output path of the compiled file in advance, re-import the source file, set MyEclipse to compile when saving, and then When saving, it can be automatically compiled

MyEclipse does not compile the solution 4. If a jar package that is not used in the project is cited, and the package is deleted by you, there will be no error but no class file can be compiled. In this case, you can delete all the packages, and then re-introduce them one by one (required), do not import all the packages at once, useless may cause adverse consequences.

MyEclipse does not compile and solve 5. I want to delete a certain The class file is regenerated and the class file is deleted, but the folders in the classes directory are opened by other programs, such as Total Commander. At this time, the compilation will not pass, and "con''t delete classes..." may be prompted under problems. Close other programs and recompile.

MyEclipse does not compile to solve 6. Another situation is to remove the JRE System Library and re-import it to compile. But what causes it is unclear.

MyEclipse does not compile and solve 7. Remove all packages in the build path. Then add jars, add libraries to add what is needed, and it starts to compile again. . .

MyEclipse does not compile to solve the output folder of 8.project->properties->java build path->source->.../WEB-INF/src is not the default, edit it to point to ../WEB-INF/classes

and click again The build project can be automatically compiled. My problem is here, I deleted the compilation directory by mistake.

MyEclipse does not compile and solve it If there is no such directory, it can be automatically compiled by manually adding some projects.

At the beginning, I only found the first 7 methods, but none of them solved my problem. I accidentally opened the "Problems" tab, It is found that the work directory is missing, add it manually, and then refresh the project.

The last two are what I found when I wrote this summary. Especially the ninth, it is more useful for projects that use CVS for version control.

. Look carefully at the xml file classpath