Java 12 intellij switch expressions doesn't work

Question

I try to use Java 12 in IntelliJ but when I try to run My app occurs error

Error:(57, 32) java: switch expressions are a preview feature and are disabled by default.
  (use --enable-preview to enable switch expressions)

I added in app configuration VM option --enable-preview but this error still occurs. I added SDK paths. Anyone have idea what I do wrong?

List<Car> sortedCars = switch (sortType) {
    case COLOR -> cars.stream().sorted(Comparator.comparing(Car::getColor)).collect(Collectors.toList());
    case MILEAGE -> cars.stream().sorted(Comparator.comparing(Car::getMileage)).collect(Collectors.toList());
    case MODEL -> cars.stream().sorted(Comparator.comparing(Car::getModel)).collect(Collectors.toList());
    case PRICE -> cars.stream().sorted(Comparator.comparing(Car::getPrice)).collect(Collectors.toList());
};

Answer 1

By default the Language Level is set to "12 - No new language feature". You need to change it to "12 (Preview) - Switch Expression" and you will get a popup to accept the Preview changes. Post which you will be able to run switch expressions in intellij.

Language Levels Settings

I am using IntelliJ IDEA 2019.1.1 (Community Edition)

Answer 2

Please make sure that the "Project language level" setting in the Project Structure dialog for your project is set to Java 12. In this case, IntelliJ IDEA will add the --enable-preview option automatically.

The VM options field in the run configuration affects how your application is launched, not how it's compiled, so adding that option there has no effect.