IntelliJ Inspector Error "Cannot Resolve Symbol" Despite Successful Compilation

IntelliJ users may experience the perplexing situation where the inspector flags "Cannot resolve symbol" errors for library imports, despite successful compilation. This issue can arise when adding a dependency to a Maven project, as demonstrated in the case of jmime.

Cause Analysis

IntelliJ uses a separate classpath for its inspection subsystem. If this classpath diverges from the compilation classpath, inspection errors may occur for symbols present in the compiled code.

Solution

To correct this issue and enable correct inspections, follow these steps:

1. Invalidate Caches: File | Invalidate Caches
2. Delete System Directory: Delete the IntelliJ system directory (typically located at C:\Users\[user]\.IntelliJIdea1003\system)
3. Re-import Maven Project: Re-import the Maven project into IntelliJ

If this method does not resolve the issue, verify the correctness of the compiled classes using javap. This tool can display the names and symbols reported by the compiled code, allowing you to determine if any discrepancies exist.