Developers' Forum

I normally run any code that prechecks a student's code in Python. Then if the code passes all the prechecks I run the student code (in whatever language ) using the Python3 subprocess. In the case of Java you have to compile first, of course. Sample Python3 code to run Java from Python is in the multilanguage question type - if you create a question of that type and click the Customise checkbox you'll see the code in the Template box and can strip out the bit you need. If you're using this approach then of course the syntax is the same as you've give above. You use a python3 question type but it has to be customised of course and under Advanced Customisation you need to set the Ace Language (which is what the student gets to see) to Java.

However, at least for the Java Method and Java Class question types you could certainly do the prechecking in Java if you wanted. Here's the prototype for a rudimentary Java method that requires the student to use a while loop rather than a for loop. I attach an xml export. This just a proof of concept: the test for a while loop is very weak. A student could defeat this by putting in a comment using the word "while". 

 

This still uses a combinator template - a per-test-case template would be a bit simpler and would allow you to print rather than raising an exception, but would be slower to run.

 

public class __tester__ {
    static String SEPARATOR = "#<ab@17943918#@>#";
    {{ STUDENT_ANSWER }}

    public static void main(String[] args) throws Exception {
        String answer = "{{ STUDENT_ANSWER | e('java')}}";
        if (!answer.contains("while")) {
            throw new Exception("You don't seem to have used a while loop!");
        } else {
            __tester__ main = new __tester__();
            main.runTests();
        }
    }

    public void runTests() {
{% for testCase in TESTCASES %}
    {
    {{ testCase.testcode }};
    {% if not loop.last %}
    System.out.println(SEPARATOR);
    {% endif %}
    }
{% endfor %}
    }
}

 

Doing a write-a-program question in Java would be harder, though. As with the Python approach, you'd have to do the prechecks first then compile and run the student code in a subprocess.