use -source 7 or higher

Question

While trying to build a project using intelliJ Ultimate 12 I am getting these errors

use -source or higher to enable diamond operator
use -source 7 or higher         


        

Answer 1

For IntelliJ IDEA Community 2018.2:

• In the project tool window, right-click on the project name to get to the Project Structure menu.
• Set Language Level to whatever version you want, and rebuild project again.

You can also use F4 as shortcut to get to the same menu.

Answer 2

In addition to the accepted answer, you may also need to change the language level under Project Structure > Modules > Sources tab.

I also needed to change the java compiler being used at the IDE level under IntelliJ IDEA > Preference > Compiler > Java Compiler to 1.7 from 1.6. The exact location of the setting will vary based on your OS and version of IntelliJ IDEA.

Answer 3

I had the same problem and was struggling. Auto-import was true, re-import of project was not working and tried all possible options. But finally i found the solution.

"Reimport All Maven Projects" did the trick for me.
You can find the option on the Maven Project tab.

Answer 4

the language level for a project is set in the project structure dialog: you want to make sure you set the language level to java 7, and the sdk accordingly

Answer 5

If using Gradle as a build automation, set following settings in build.gradle and re-import your project:

sourceCompatibility = 1.7

targetCompatibility = 1.7

Answer 6

None of the above worked for me.

I had to explicitly add the following plugin statement to my pom.xml:

  <plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-compiler-plugin</artifactId>
    <configuration>
      <source>1.7</source>
      <target>1.7</target>
    </configuration>
  </plugin>

(Well, IDEA made it for me when I clicked the red help lamp and selected "Set project Java level to 7", so maybe try that if this also doesn't work).