void main() {
    throw new RuntimeException("Crash!");
}

¹

You may be wondering why the names "Exception" and "RuntimeException" instead of the probably easier to understand "CheckedException" and "UncheckedException." Java was made by humans and initially - as I understand it - "normal" exceptions were expected to be checked. It was only exceptions that came from "The Java Runtime" that would be unchecked. So that is where the name "RuntimeException" comes from. It just very quickly became a choice that was too late to change without breaking all the Java code in the world.