@Override is not allowed when implementing interface method

I have the problem mentioned in the title. You could say that this thread duplicates another one: How do I turn off error validation for annotations in IntelliJ IDEA?

But the solution given there doesn't work. They say that I need to take the following action:

> In the Project Structure | Project dialog, change the Project language Level to 6.0 - @Override in interfaces.

However, the Project language Level is 6.0 at the moment, but I still see the error.

Vic, here is the window and there is no JVM version right under Language level (unfortunately I can't post images because I have 10 reputation)

If your project has multiple modules, also check that every module uses language level 6 or above, or use the project's language level (see Project Settings > Modules > xxx > Language level).

You may need to reload your project once it is modified.

At your module/project, Right click to see context menu:

Choose Open Module Settings or press F4. In setting windows:


Set value for Choose Language level section.

You also should check Project language level by this way: press Ctrl+Alt+Shift+S

A simpler solution - inline

1. Put the caret on the @Override word and move the caret on the left side until the red bulb icon will appear. Then click on it.

2. Click on Set language level to 6 - Override in interfaces

---

The method above is an alternative to the following approach:

1. Go to File > Project Structure... or press Ctrl+Alt+Shift+S

2. Go to Project Settings > Modules > Sources > Language level and choose any level that is 6 or greater than 6.

If you are using maven, add maven compiler plugin to the project's pom.xml file.

<build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.1</version>
                <configuration>
                    <source>1.7</source>
                    <target>1.7</target>
                </configuration>
            </plugin>
        </plugins>
    </build>

This solved the issue for me.

There's also a language level for every module. Please check your module settings in the Project Structure.

I ran into this problem for the first time while using a multi module maven project. As other answers / IDE suggested, we need to set the language level.

Rather than changing the setting of IDE, to make the project IDE agnostic, I update the parent pom with below properties, which solved the issue.

<properties>
    <maven.compiler.source>1.8</maven.compiler.source>
    <maven.compiler.target>1.8</maven.compiler.target>
</properties>

In JIdea 2020.1.2 and above,

1. Go to Project Structure [ Ctrl+Alt+Shift+S ]
2. Select Modules sub section
3. Select each module
4. Under sources-section, check Language Level
5. Change the Language Level as required

NOTE:

If you get below error after this change,

Error:java: Compilation failed: internal java compiler error

You have to change the target bytecode version as well.

1. Go to Settings [ Ctrl+Alt+S ]
2. Select Java Compiler
3. Select module in the table
4. Change the byte-code version to map what you selected in the previous step for language-level