495
votes

When running a JUnit test, using IntelliJ IDEA, I get

enter image description here

How can I correct this?

  • Using SDK 1.7
  • Module language level is 1.7

Maven build works fine. (That's why I believe this in IDEA configuration issue)

18

18 Answers

748
votes

Most likely you have incorrect compiler options imported from Maven here:

compiler options

Also check project and module bytecode (target) version settings outlined on the screenshot.

Other places where the source language level is configured:

  • Project Structure | Project

project

  • Project Structure | Modules (check every module) | Sources

sources

Maven default language level is 1.5 (5.0), you will see this version as the Module language level on the screenshot above.

This can be changed using maven-compiler-plugin configuration inside pom.xml:

<project>
  [...]
  <build>
    [...]
    <plugins>
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-compiler-plugin</artifactId>
        <configuration>
          <source>1.8</source>
          <target>1.8</target>
        </configuration>
      </plugin>
    </plugins>
    [...]
  </build>
  [...]
</project>

or

<project>
  [...]
  <properties>
    <maven.compiler.source>1.8</maven.compiler.source>
    <maven.compiler.target>1.8</maven.compiler.target>
  </properties>
  [...]
</project>

IntelliJ IDEA will respect this setting after you Reimport the Maven project in the Maven Projects tool window:

reimport

359
votes

IntelliJ 15, 2016 & 2017

Similar to that discussed below for IntelliJ 13 & 14, but with an extra level in the Settings/Preferences panel: Settings > Build, Execution, Deployment > Compiler > Java Compiler.

enter image description here

IntelliJ 13 & 14

In IntelliJ 13 and 14, check the Settings > Compiler > Java Compiler UI to ensure you're not targeting a different bytecode version in your module.

enter image description here

61
votes

In IntelliJ IDEA 14.1 the "Target bytecode version" is in a different place.

The following change worked for me:

File > Settings... > Build, Execution, Deployment > Compiler > Java Compiler : change Target bytecode version from 1.5 to 1.8

enter image description here

enter image description here

42
votes

Have you looked at your build configuration it should like that if you use maven 3 and JDK 7

<build>
    <finalName>SpringApp</finalName>
    <plugins>
        <plugin>
            <artifactId>maven-compiler-plugin</artifactId>
            <configuration>
                <source>1.7</source>
                <target>1.7</target>
            </configuration>
        </plugin>
        ...
    </plugins>
    ...
</build>
23
votes

I ran into this and the fix was to go to Project Settings > Modules > click on the particular module > Dependencies tab. I noticed the Module SDK was still set on 1.6, I changed it to 1.7 and it worked.

15
votes

I've found required options ('target bytecode version') in settings > compiler > java compiler in my case (intelij idea 12.1.3)

10
votes

Modify the compiler setting file of the project in the following path and change the 'target' to 1.7:

/project/.idea/compiler.xml

<bytecodeTargetLevel>
  <module name="project-name" target="1.7" />
</bytecodeTargetLevel>
5
votes

I resolved it by setting the field blank:

Settings > Compiler > Java Compiler > Project bytecode version

Than IntelliJ uses the JDK default version.

4
votes

From one moment to the other I also got this error without a clear reason. I changed all kinds of settings on the compiler/module etc. But in the end I just recreated the IntelliJ project by reimporting the Maven project and the issue was solved. I think this is a bug.

IntelliJ 12 129.961

4
votes

I've hit this after just minor upgrade from IntelliJ IDEA 14 to v14.1. For me changing an edit of top/parent pom helped and then clicked re-import Maven (if it is not automatic).

But it maybe just enough to Right Click on module(s)/aggregated/parent module and Maven -> Reimport.

2
votes

I resolved bellow method

File >> Project Structure >> Project >> Project Language Level --> do set proper version (ex: 1.5)

1
votes

check .idea/misc.xml sometimes you need to change languageLevel="JDK_1_X" attribute manually

1
votes

If it is a Gradle project, in your build.gradle file, search for following settings:

sourceCompatibility = "xx"
targetCompatibility = "xx"

For all subrpojects, in your root build.gradle file, you may put:

subprojects { project ->
    sourceCompatibility = "1.7"
    targetCompatibility = "1.7"
}

Although you can manually set language levels in Idea > Settings, if it is a Gradle project, Idea automatically synchronizes module .iml files from Gradle settings ( tested with Idea 15+). So all your manual changes are overriden when gradle is refreshed.

Based on Gradle documentation, if these are not set, then current JVM configuration is used.

1
votes

I found another way to run into this error. You can get this if you have been re-organizing your directory structure, and one of your poms is pointing to the old parent which no-longer configures javac (because that configuration was moved to a middle level). If this happens the top level defaults to 1.5 and the misbehaving lower level pom inherits it.

So another thing to check when you see this error is that your pom structure is matching your directory structure properly.

1
votes

If Maven build works fine, try to synchronizing structure of Maven and IntelliJ IDEA projects.

In the Maven tool window, click refresh button refresh. On pressing this button, IntelliJ IDEA parses the project structure in the Maven tool window.

Note that this might not help if you're using EAP build, since Maven synchronization feature may be broken sometimes.

1
votes

You need to change Java compiler version in in build config.

enter image description here

0
votes

Make sure right depency is selected. File > Project Structure

Select your project and navigate to Dependencies tab. Select right dependancy from dropdown or create new.

0
votes

If all the previous solutions haven't worked for you (which was my case), you can delete intellij config files:

  • project_directory/.idea/compiler.xml
  • project_directory/.idea/encodings.xml
  • project_directory/.idea/misc.xml
  • project_directory/.idea/modules.xml
  • project_directory/.idea/vcs.xml
  • project_directory/.idea/workspace.xml
  • etc.

Intellij will regenerate new ones later. However, BE CAREFUL, this will also delete all intellij configuration made on the projet (i.e: configuration of debug mode, ...)