Why so red? IntelliJ seems to think every declarat

问题:

I just installed and re-installed IntelliJ. Every Java file is coming up RED. I checked the JDK; it is at 1.6.##. The maven clean install build worked just fine.

I'm getting the usual highlighted errors. On every declaration:

Cannot resolve symbol SomeEntityBean/Bean

and on every method:

Cannot resolve method SomeFunction()

How do I fix these false errors?

回答1:

IntelliJ sometimes gets confused all by itself, even without the external changes Korgen described (though that is a good way to consistently reproduce it).

Click File -> Synchronize, and IntelliJ should see that everything is okay again.

If that doesn't work, IntelliJ's caches might be corrupt (this used to happen a lot more often than it does now); in that case, regenerate them by

Clicking File -> Invalidate Caches and restarting the IDE

(though loading the project will take a while while the caches are recreated).

回答2:

I experienced this when I updated my JDK manually and removed the previous JDK

Solution

• In the IntelliJ editor, click on the red keyword (Integer for example) and press ALT + ENTER (or click the light bulb icon)
• select Setup JDK from the intentions menu

• click on Configure

• In my case, the JDK path was incorrect (pointed on /opt/jdk1.7.0_51 instead of /opt/jdk1.7.0_65)

• Click on the ... and browse to the right JDK path

• Let's clear the cache:

And everything should be back to life :)

回答3:

IntelliJ sometime gets confused after importing maven projects and then changing poms externally or generating sources outside IntelliJ.

You might want to try a maven->force reimport from within intellij on the project root

回答4:

My problem solved by changing jdk to default , like this. Open Jdk was installed but don't know why intellij set configuration to java-8-openjdk-amd64. This was the problem.I have changed to default-java and no more red error.

回答5:

I had the same problem after changing JDK from 1.6 to 1.7 in my pom.xml and setting Maven 3 path + JDK project settings to 1.7.

What did it for me was => File -> Invalidate Caches and Restart

PS: problem occured again, so i just reimported the full project after deleting the .idea folder and now it works fine as usual :)

回答6:

I have IntelliJ IDEA 12.x on the Mac and I use Maven 3 and I get the red highlighting over my code even though the Maven build is fine. None of the above (re-indexing, force import, etc.) worked for me. I had to do the following:

Intellij -> Preferences -> Maven -> Importing
    [ ] Use Maven3 to import projects

I have to check the Maven3 import option and that fixes the issue.

回答7:

Check that you have a proper JVM SDK setting in IntelliJ Properties. If invalidate-cache-and-restart isn't enough, check that your are using the proper JVM SDK, such as Java 1.7.

Look in: Preferences -> IDE Settings -> Scala -> JVM SDK

Or right click your project -> Open Module Settings -> Project Settings -> Project -> Project SDK -> (Set to Java 1.7)

Open Module Settings -> Platform Settings -> SDKs -> (Ensure that there is a Java 1.7, otherwise you'll need to add it)

If you've made a change, then it's probably best to re-run Invalidate Cache & Restart.

回答8:

I was trying to use all the advices above, but unfortunately no one helped me. So finally I've decided to delete my intelij workspace and create the new one - it helped :) But earlier I was also doing cleaning the cache, reimporting maven projects, cleaning projects and rebuilding them.

回答9:

I had the same problem.

In my case the problem was with maven home directory and user settings file in Intellij Settings under Maven. I had installed Maven not in the default directory and I had also changed the location of the settings.xml file. This should also be changed in the IntelliJ Settings.

Hope this helps also.

回答10:

In my case, getter and setter dependencies were coming through lombok plugin (Using java with Spring). And in the new installation of intellij idea, I had not installed the lombok plugin. Installing the lombok plugin fixed it for me.

回答11:

I had the same problem and after trying all of the above suggestions, it turned out that my IntelliJ installation had not picked up my JAVA_HOME system variable, and it had no SDK/JDK set.

I fixed it by following these instructions: Configuring Global, Project and Module SDKs

回答12:

For me it was the JDK that was not set up correctly. I found a solution that I documented here: https://stackoverflow.com/a/40127871/808723

回答13:

Yet another work around!One of the solutions, which suggested clicking Alt Enter didn't have the Setup JDK for me, but Add ... to classpathworked.

回答14:

These 3 steps almost always work for me :

Step 1 - File -> Invalidate cache/ Restart

Step 2- If you see that in File -> Project Structure -> SDKs the SDK is red, Try to configure it properly as explained here

Step 3 - Update Java versions in

a) File -> Project Structure -> Project
b) File -> Project Structure -> Module (Sources and Dependencies tab)
c) Preferences -> Java Compiler

回答15:

The issue was that the file I was trying to import was so large that IntelliJ wouldn't run any CodeInsights on it.

Setting the idea.max.intellisense.filesize option to a higher value as per the instructions on this answer resolved my issue.

回答16:

I had the same issue I was using JDK 1.9 with IntelliJ 14, I solved reinstalling Java with latest version of JDK 1.8(1.8.0_161 in this case)

I also removed the 1.9 version from

HKEY_CURRENT_USER\Software\JavaSoft\JRE\Security Baseline

回答17:

I had the same issue, what fixed it for me was:

Go to File>Setting>Maven, I set the Maven home directory, settings file and local repo.

Go to Maven Projects and click on Reimport All Maven Projects

This did the trick!

回答18:

I had this problem on a fresh install of IDEA. I thought it had brought its own JDK or would be able to find the one already on the machine, but apparently not (not sure what the checkbox in the install dialog did, now). When I clicked on the lightbulb and clicked the "Setup JDK" button and then clicked "Configure," it revealed that it was trying to get the JDK from

C:\Program Files\JetBrains\IntelliJ IDEA Community Edition 2018.1\jre64

I browsed around, trying a few folders in the JetBrains tree, but at least the dialog was smart enough not to let me apply any (including the original), saying they were not valid locations for a JDK. So I browsed over to the Java tree and tried that, and it accepted this:

C:\Program Files\Java\jdk1.8.0_40

After I OK'ed the config, it didn't appear to have worked; so I went to try invalidating the IDEA cache and restarting (as described in other answers), and it told me that I had background tasks running. So I canceled out of the invalidation, and while I was doing that, whatever recompilation or database updating it was doing completed, and all the red in the edit window went away. So it takes a few seconds (at least) for the JDK config to settle out.

回答19:

Try to delete the .IntelliJIdea15(depends on version) from C:\Users\Username

When you start IntelliJ it will create the folder again.

回答20:

This is if you see Java classes in red and get this error, "Cannot resolve symbol".

If you're importing projects into IntelliJ and none of the above solutions worked for you then give this a try. This is what worked for me when everything else failed.

Go to to your project folder and rename/delete the .idea folder which has the idea settings for your project. This would have been created from your old IntelliJ version. Once you have renamed/deleted the .idea folder, import your project into IntelliJ. You should not see any errors for your Java classes now. Hope this helped.

回答21:

Yet another solution on IntelliJ Ultimate 2018.2

• Hover over the import marked red
• Select dropdown arrow on the popup that appears on left (below)
• Choose "Add library ... to classpath"