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Intellij inspection gives "Cannot resolve symbol" but still compiles code

java
intellij
cache
maven
Nikita BarsukovbyNikita Barsukov·Sep 18, 2024
TLDR

Wipe out the "Cannot resolve symbol" complication in IntelliJ swiftly. Head to File > Invalidate Caches / Restart..., and select "Invalidate and Restart" to align IntelliJ's background with your up-to-the-minute codebase.

// When in doubt, flush it out! // File > Invalidate Caches / Restart... > Invalidate and Restart

Clear-cut diagnosis and solutions

It's all ‘cache’ talk

IntelliJ relies on a system cache for keen performance. A stale or tainted cache can be the culprit behind the "Cannot resolve symbol" conundrum. Here’s your plan of action, invalidate the cache:

// It's like doing a spring cleaning! 😉 // File > Invalidate Caches / Restart... > Invalidate and Restart

When there’s a will, there's a way...and a system directory

For more obstinate situations, consider taking the bold step of deleting the IntelliJ IDEA system directory. This measure resets the entire environment from scratch, resolving any chronic discrepancies between your project and IntelliJ's index.

Maven your way back

After you’ve cleared the cache or fully reset the system directory, towel off and reimport your Maven project. This ensures that the project's configuration remains in-sync with IntelliJ's expectations. It's important here not to forget to keep Java Dev Kit (JDK) versions the same across your IntelliJ and Maven for an uninterrupted workflow.

Analysis with ‘javap’

For a quick dive into your compiled classes without getting your feet wet, utilize the javap command-line tool. It acts like your own personal assistant, identifying any bytecode abnormalities which may contribute to the inspection error.

The labyrinth of library configurations

Make sure all the ducks are in a row. Check if the library called "jmime" is duly part of the "Libraries" section in IntelliJ's Project window. A missing or incorrectly configured library could lead IntelliJ to flunk the symbol resolution test.

// Are we forgetting something? Let's check, // Go to Project > Libraries > (should see "jmime" here)

Maven your project again

Remember to brush your teeth twice a day and keep your project files in sync using the mvn -U idea:idea command for Maven or simply refresh your Gradle tool pane. Brush IntelliJ off your shoulder, helping it identify all the dependencies it needs to sail through.

A walkthrough of cache permissions

Make sure you have the keys to the kingdom, aka access permissions to the IntelliJ cache folders. Denied permissions can prevent IntelliJ from updating its memory, resulting in a failed symbol resolution.

Away from IntelliJ, into the wild

Sometimes, stepping out of your comfort zone helps you find what you’re looking for. Try building the project outside of IntelliJ to bypass any cache-related permission battles nested within the IDE.

Advanced troubleshooting

Transformers — project structures in disguise

An incorrectly updated project structure after adding Maven dependencies manually or dealing with non-Maven projects can tumble you down the rabbit hole of inspection errors. Ensure that jars are correctly configured in the IDE and Maven dependencies are accurately enlisted in your pom.xml.

Unmasking jar files

Take a look under the hood of your jar files' manifests. They could hold invaluable clues to class recognition issues. Kind of like that hidden stash of cookies behind the coffee mugs, except this one has all the potential to throw off IntelliJ — especially when a jar gets corrupted or contains unusual entries.

Maven and Gradle to the rescue

Bring calm to the chaotic Maven project by right-clicking within your code editor, selecting Maven and opting for "Reimport". If you're dealing with Gradle projects, just refresh your Gradle Tool pane to sync any changes made in build.gradle. Keep the vampires away by ensuring that your IDE knows about every dependency change.

Deciphering the .iml file

The IntelliJ module file (*.iml) can sometimes be stealthier than you think. Erasing the main.iml file and opening the project afresh can compel IntelliJ to refresh project settings, unravelling the issue at hand.