Config.java updated

package com.kurzdev.vertretungsplanapp.basics;

import com.kurzdev.vertretungsplanapp.basics.UserHandler;

import org.json.JSONArray;
import org.json.JSONObject;
import java.io.*;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.util.ArrayList;

public class Config {

    public Config(){
    }

    public ArrayList<String> loadDataUPC(){

        if(this.getData()){
            return returnJSONDataUPC();
        }else{
            return null;
        }
    }

    public ArrayList<String> loadDataCourses(){

        if(this.getData()){
            return returnJSONDataCourses();
        }else{
            return null;
        }
    }

    private String loadJSON(){

        try {
            File json_file = new File(System.getProperty("user.dir") + "/src/Config.json");
            String json_raw = new String(Files.readAllBytes(Paths.get(json_file.toURI())), "UTF-8");

            return json_raw;

        } catch(IOException e){
            System.out.println("An IOException occured: " + e.getMessage());
            return null;
        } catch(Exception e){
            System.out.println("An unknown exception occured: " + e.getMessage());
            return null;
        }
    }

    /*
    Method to write data to an desired JSON file
    @param username: Argument used to log into Moodle
    @param password: Argument to authenticate on Moodle
    @param class_data: Argument regarding data about a certain class/grade
    @param course_data: Argument/List consisting of one's courses - to-be-used in MyFilter
     */
    @SuppressWarnings("unchecked")
    private void writeJSON(String username, String password, String class_data, ArrayList<String> course_data){

        JSONObject obj = new JSONObject();

        if(username.equals("")){
            obj.put("username", "");
        }else if(password.equals("")){
            obj.put("password", "");
        }else if(class_data.equals("")) {
            obj.put("class", "");
        }else if(course_data.isEmpty()){
            obj.put("courses", "");
        }else{
            obj.put("username", username);
            obj.put("password", password);
            obj.put("class", class_data);

            JSONArray course_list = new JSONArray();
            for(String elements : course_data){
                course_list.put(elements);
            }
            obj.put("courses", course_list);

            try(FileWriter file = new FileWriter(System.getProperty("user.dir") + "/src/Config.json")){
                file.write(obj.toString());
                file.flush();
            }catch(IOException e){
                System.out.println("An IOException occured: " + e.getMessage());
            }catch(Exception e){
                System.out.println("An unknown exception occured: " + e.getMessage());
            }

        }
    }

    /*
     Method used to get desired data for JSON file
     */
    private Boolean getData(){
        if(!this.checkJSON()){
            UserHandler uHandler = new UserHandler();

            String username = uHandler.getUsername();
            String password = uHandler.getPassword();
            String classes = "3";

            ArrayList<String> course_list = new ArrayList<>();
            course_list.add("Wer das liest ist dumm.");

            this.writeJSON(username, password, classes, course_list);
            return true;
        }else if(this.checkJSON()){
            return true;
        }else{
            return false;
        }
    }

    private Boolean checkJSON(){
            String raw_json = this.loadJSON();
            if(raw_json == null){
                System.out.println("JSON is null.");
                return false;
            }else {
                JSONObject jobj = new JSONObject(raw_json);

                String class_data = jobj.get("class").toString();
                String username = jobj.get("username").toString();
                String password = jobj.get("password").toString();

                JSONArray jarray = jobj.getJSONArray("courses");
                ArrayList<String> courses = new ArrayList<>();

                for(int i = 0; i<jarray.length(); i++){
                    courses.add(jarray.getString(i));
                }

                if(username.equals("")){
                    return false;
                }else if(password.equals("")){
                    return false;
                }else if(class_data.equals("")) {
                    return false;
                }else if(courses.isEmpty()){
                    return false;
                }else {
                    return true;
                }
            }
    }

    private ArrayList<String> returnJSONDataUPC(){

        String raw_json = this.loadJSON();
        JSONObject jobj = new JSONObject(raw_json);

        String class_data = jobj.get("class").toString();
        String username = jobj.get("username").toString();
        String password = jobj.get("password").toString();

        final ArrayList<String> final_list = new ArrayList<>();
        final_list.add(username);
        final_list.add(password);
        final_list.add(class_data);

        return final_list;
    }

    private ArrayList<String> returnJSONDataCourses(){

        String raw_json = this.loadJSON();
        JSONObject jobj = new JSONObject(raw_json);

        JSONArray jarray = jobj.getJSONArray("courses");
        ArrayList<String> courses = new ArrayList<>();

        for(int i = 0; i<jarray.length(); i++){
            courses.add(jarray.getString(i));
        }

        return courses;
    }

}