Lambda expression not working with IntelliJ - intellij-idea

Question

Im trying to use the IntelliJ IDE to write a JavaFX program, however when the lambda expression is used, I get an error message followed by a compile error
original code
error message
Overrides method in javafx.event.EventHandler
package sample;
import javafx.application.Application
import javafx.scene.control.*;
import javafx.stage.Stage;
public class Main extends Application {
public static void main(String[] args) {
launch(args);
}
#Override
public void start(Stage window) throws Exception {
window.setTitle("Window Title");
Button button = new Button("Click me");
button.setOnAction(e -> System.out.println("Hello World"));
}
}
compile error
To specify, it is set up as a JavaFX program, in project structure I have the Project SDK set to 10.0.1 and I have the language level set to 8
Is there something missing that I need in order to use lambda expressions?

Answer 1

Change the project language level to 10:

Answer 2

On your application folder build.gradle Add compileOptions inside android:
android {
compileOptions {
sourceCompatibility JavaVersion.VERSION_1_10
targetCompatibility JavaVersion.VERSION_1_10
}
}

Answer 3

I had the same problem.
Indeed under File > Project Structure > modules, the Language level was set to 7 - Diamonds, RM, multi catch.
But since the project is built with maven, the root problem was located in maven pom.xml
<maven.compiler.source>1.7</maven.compiler.source>
<maven.compiler.target>1.7</maven.compiler.target>
just set the value to 1.8 and the problem is solved.