Using Java interface means using Java classes and Java objects as well as methods applicable to them within Querix 4GL. To be able to do this you must first import a Java class you want to use and then create the corresponding Java objects.
Unlike Querix 4GL, the Java language is case sensitive. Therefore, when you write the name of a Java package, class, method, or field in a .4gl source, it must match the exact name as if you were writing a Java program. Attempting to compile a .4gl source containing a Java identifier typed in the wrong case will result in a compilation error.