Android Studio Java Syntax Highlighting Not Working

You should do invalidate caches and restart. It will work.

To solve this kind of issue, I had to trigger: File -> Repair IDE

I ran into this problem today. In my case it was caused by Android Studio changing my "MainActivity.java" file from a Class to a Singleton. If the file is a Class its icon in the editor or project listing will have a "c" in a light blue circle. If it is a Singleton it has a "j" in a grey rectangle. To resolve it I did the following:

1. copied the file's contents into notepad
2. deleted the singleton file BUT I did not select "safe delete" since I don't want Android Studio to do anything clever
3. created a new Java Class file with the same name as the original file
4. replaced the contents of the new file with what I put into notepad in step 1

Then everything started working again.

Before this I'd tried the invalidation/restart and disabling power save mode but they did not work for me. I even tried rebooting my computer several times.

If you have installed SQLDelight plugin on your Android Studio, uninstall it. It will resolve your problem, and install SQLDelight again when you need that.

To quickly refresh or enable syntax highlighting, I accidentally did: Ctrl + Alt + S to go to settings, then in Plugins -> Installed disable any plugin and then Enable it and Apply.

This worked for me.

None of these worked on the 2024 version. I had to uninstall Android Studio, clear all caches and application support on Mac, and reinstall it again to solve this issue.

１. Remove cache

(in my case it happened on macOS)

rm -rf ~/.gradle/cache/*

２. Execute the following steps

1. open the target file on Android Studio
2. ctrl + a
3. ctrl + x
4. ctrl + s
5. ctrl + v

３. Restart Android Studio

It works for me.

My issue were two new Grazie plugins I enabled. Disabling them solved the problem

i had the same problem and tried almost anything i could. Then i realized i had a folder named "app", after moving "src" folder out of app the problem was fixed.

after moving the folders

Deleting the Android Studio app and then re-downloading it worked for me.

Please remove and reinstall Android Studio. I had installed multiple versions of Android Studio, and it was my problem. I deleted all of these and installed the new version (Koala); everything is fine now( on mac )!

TL;DR - disable the Package Checker plugin. Or maybe all plugins to see if it helps at all (kinda, run IDE in the "safe mode")

Longer story below:

I had a very similar problem, quite irritating one, and this question is the closest to what I had. So writing my findings here - maybe it will help someone else too.

I have IntelliJ Community Edition (tried versions from 2022 to 2024) in a corporate environment, behind firewalls, proxies, etc, i.e. probably quite tough environment for the IntelliJ which might try to access network for various reasons, with some sites and HTTP requests working and some not.

Anyway, one day the syntax hightlighting and overall the code inspection went out of the window. Correct parts of the files might be red, incorrect are not highglighted. Cleaning up cache the did not help. Re-cloning the repo, full reinstall and upgrading to the latest version of IntelliJ did not help.

In the IntelliJ logs, I saw this exception at pretty much every startup:

SEVERE - #c.i.c.d.i.PassExecutorService - java.lang.IllegalArgumentException: JBAccountInfoService is unavailable 
java.lang.IllegalArgumentException: java.lang.IllegalArgumentException: JBAccountInfoService is unavailable 
  at  java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
...
  at  com.intellij.codeInsight.daemon.impl.ProgressableTextEditorHighlightingPass.doCollectInformation(ProgressableTextEditorHighlightingPass.java:80)
  at  com.intellij.codeHighlighting.TextEditorHighlightingPass.collectInformation(TextEditorHighlightingPass.java:57)  
...

So, looked like highlighting was stumbling upon some account problem?? It was very puzzlying.

Fortunately, the answer above about the Grazie plugin gave me the clue. Disabling Grazie did not change the situation for me, but gave me an idea to disable all the plugins, which suddenly returned the situation back to normal.

After switching the various plugins on/off, I found the culprit - for me it was the Package Checker plugin. Some bundled plug-in, I don't even know what it's doing, and I got absolutely no idea why it affects the highlighting.

Also, after a closer examination of the call stack for the exception mentioned above, I found that indeed it comes out of that plugin, since there were these lines too:

...
  at com.intellij.packageChecker.service.PackageChecker$Companion.getInstance (PackageChecker.kt:311)
  at com.intellij.packageChecker.service.HeadlessSynchronizationService.<init>(HeadlessSynchronizationService.kt:32)
...

Just, iniatially I did not pay attention to these packageChecker lines because nothing there gives a clue that it's some kind of a plug-in (it says just com.intellij.packageChecker! Just that was not enough to catch my eye). But, now when I know about this plug-in - the exception definitely comes from it, as the call stack says.

Anyway, disabling the Package Checker plug-in helped me. If someone else's got a similar story and disabling the Package Checker plugin does not help, I'd recommend to disable all the plugins first - if it helps, find the bad boy by switching them on and off with binary search approach.

Just be sure your plugin version and lib version in gradle file are the same. I realize my sqlDelight version vas 2.0.0 in gradle file but my plugin version vas 2.0.2. When I changed 2.0.0 to 2.0.2 it worked.