Error loading Turtle File in Android Studio

Question

I am attempting to load a Turtle file into Android studio and use the Androjena library to run queries against the Turtle file. I am able to do this in Eclipse with JavaFX with no issue. However, in the Intellij IDE I am getting a FATAL error which obviously crashes my app. I have a method called runQuery() that is called in order to run a query on the File:

public String runQuery(){
             String stringQuery = "PREFIX foaf: <http://xmlns.com/foaf/0.1/> \n" +
            "PREFIX dbo: <http://dbpedia.org/ontology/> \n" +
            "SELECT ?birthDate WHERE { \n" +
            "?barack foaf:name \"Barack Obama\"@en .\n" +
            "?barack dbo:birthDate ?birthDate \n" +
            "}";


             String answer = "";
             Model model = FileManager.get().loadModel("sample_pres.ttl", "TTL");

             Query query = QueryFactory.create(stringQuery);
             try {
                  QueryExecution qexec = QueryExecutionFactory.create(query, model);
                  ResultSet results = qexec.execSelect();
                  while(results.hasNext()) {
                        QuerySolution soln = results.nextSolution();
                        Literal answerLiteral = soln.getLiteral("birthDate");
                        answer = answerLiteral.toString();

        }
    }

            catch(Exception ignore) {

    }


    this.answer = answer;
    return answer;
}

The line of code that is giving me issues is the FileManager.get().loadModel() line. Here is the Exception that I am getting:

com.hp.hpl.jena.shared.NotFoundException: Not found: sample_pres.ttl

So I am gathering that Android is not finding the file, although the file is in my Assets folder. I am assuming that I don't/cannot use the AssetManager since I am not attempting to include a FileInputStream. So I'm fairly stuck at this point. Here is a picture of my project structure:

I added the assets folder under app/src/main in my project structure. I am relatively new to Android Studio and I know that in JavaFX from eclipse I could simply use the absolute path for the File in order to access it, and I know that this obviously will not work in Android Studio. I couldn't find one example however of loading a Turtle file from a local source in the Android project (my assets folder) and executing a query. Every example or question on this site appears to be in regards to running a query from an external endpoint over an internet connection. So This is partially why I am confused. I am not sure how to run the query from a Local source in Android studio and reference the Turtle file from my assets folder in order to avoid the com.hp.hpl.jena.shared.NotFoundException

Answer 1

I found the answer. The issue is that asset files in android studio cannot be read in android studio. They have to be converted to a FileOutputStream, even when working with .ttl files and reading them in turtle. Here is an example of the code:

 String filePath = context.getFilesDir() + File.separator + "my_turtle.ttl";
    File destinationFile = new File(filePath);
    FileOutputStream outputStream = new FileOutputStream(destinationFile);
    AssetManager assetManager = context.getAssets();
    InputStream inputStream = assetManager.open("sample_3.ttl");
    byte[] buffer = new byte[1024];
    int length = 0;
    while((length = inputStream.read(buffer)) != -1){
        outputStream.write(buffer,0,length);
    }
    inputStream.close();
    outputStream.close();



    Model model = null;

    model = FileManager.get().loadModel(filePath,"TTL");

    Query query = QueryFactory.create(stringQuery);

    QueryExecution qexec = QueryExecutionFactory.create(query, model);
    ResultSet results = qexec.execSelect();
    while(results.hasNext()) {
            QuerySolution soln = results.nextSolution();
            Literal answerLiteral = soln.getLiteral("abstract");
            answer = answerLiteral.toString();
            System.out.println(answer);


        }



    if(!answer.equals("")){
        this.answer = answer;
        return answer;
    }
    else{
        return "I could not find an answer";
    }