JavaLang.java

public class JavaLang extends ProgrammingLang {
    public void compileAndRun() {
        System.out.println(JavaLang.class.getName());
        System.out.println("Compiling...");
        System.out.println("Running...");
    }
}

JavascriptLang.java

public class JavascriptLang extends ProgrammingLang {
    public void run() {
        System.out.println(JavascriptLang.class.getName());
        System.out.println("Running...");
    }
}

Pattern Matching (JDK 14 Only)

public class PatternMatching {
    public static void main(String[] args) {

        ProgrammingLang lang = new JavaLang();

        if (lang instanceof JavaLang test) {
            test.compileAndRun();
        } else if (lang instanceof JavascriptLang test){
            test.run();
        }

    }
}

ProgrammingLang.java

public class ProgrammingLang {

}