Intellij手动添加jar会出现编译错误

Question

I am using Maven in my project, and for some reasons, some additional jars should be added manually (I have followed the step like Correct way to add external jars (lib/*.jar) to an IntelliJ IDEA project ).

The package can be imported successfully. However, the compilation error happens, which indicates the package does not exist and cannot find the symbol of the used object.

I have tried the following tips but it remain unchanged:

1. Invalid caches / restarts
2. reimport
3. delete .idea file and .iml file

The scenario is quit similar to this one : https://intellij-support.jetbrains.com/hc/en-us/community/posts/206821195--beginner-question-including-external-jar-compile-error .

Please see the following sample images. It may run successfully but cannot be compiled well.

Answer 1

The reason is that when you add a library manually via IntelliJ, only IntelliJ knows about them and when you compile your code using Maven, it can't be find by Maven because Maven only searches for dependencies you defined in pom.xml.

You should install your libraries in your (at least) local maven repository and add them as a normal dependency in your pom.xml. Then you don't need to add them manually in IntelliJ.

You should follow the steps mentioned at Guide to installing 3rd party JARs

Update: Also you should note that if you're working as a team, you should install this on the local maven repository of all developers (which is not practical). The best solution is to install a Maven repository (eg Nexus, Artifactory or Archiva) in a server on your local network and upload your private jar files on those servers. Then all developers can define the address of the local Maven repository server in their local Maven settings and use artifacts/libraries from that servers. Plus it works as a local cache/proxy to fetch any Maven artifacts and prevents unnecessary calls to public maven repositories.