Can't compile with jdk 11 in IntelliJ, cannot find symbol

Question

I set the JDK 11, it compiles until I use the new method of Java 11 isBlank() of a String when I use that method this error appears when compiling, I tried cleaning the JDK installations, cleaning caches from IntelliJ, rebuilding but nothing helps. The error is:

Answer 1

Try setting compiler target bytecode version to 11.

Go to Settings - Build, Execution, Deployment - Compiler - Java compiler and set target bytecode version of your module to 11

Answer 2

You should check following things:

1. You've JDK11 defined as one of the SDKs:
2. Your project's default SDK is JDK11 and your projects default language level is 11:
3. Your module language level is also 11.

And if you use Maven, check that your compiler plugin "source" and "target" properties in your pom.xml are 11. Your module language level configuration is imported from that pom.xml configuration in such a case

     <properties>          <maven.compiler.source>11</maven.compiler.source>          <maven.compiler.target>11</maven.compiler.target>      </properties> 

or

     <plugin>         <groupId>org.apache.maven.plugins</groupId>         <artifactId>maven-compiler-plugin</artifactId>         <version>3.8.0</version>         <configuration>             <source>11</source>             <target>11</target>         </configuration>      </plugin> 

In case your pom.xml had wrong source or target level you may need to do Right-click | Maven | Reimport after changing that pom.xml. In case you use Gradle you should check that you have a similar configuration.

4. Your module SDK is Project JDK11 or just JDK11

Tested with Maven 3.5.4 in IntelliJ IDEA 2018.2.4