What will happen if Java code accesses an internal field of an object implemented in Kotlin?

There will be a compilation error.

// Kotlin code
class MyClass {
    internal val internalProperty: String = "Internal value"
}

// Java code trying to access internal property
public class JavaClass {
    public void accessInternalProperty() {
        MyClass myObject = new MyClass();
        // This line will cause a compilation error
        // System.out.println(myObject.internalProperty);
    }
}

The internal visibility in Kotlin means that the class member is visible only within the same module. From Java's perspective, this is similar to package-private visibility, but it applies to all classes within the same Kotlin compilation module, not just within the same package. The Java compiler does not have direct access to Kotlin internal members from other modules (even if they are in the same package), which results in a compilation error. The Kotlin compiler generates special names for internal members that include the module name to prevent access from outside the module.