Jsontest.java

import org.json.JSONObject;
import org.json.JSONArray;
import processing.core.PApplet;

import java.io.*;
import java.util.ArrayList;

public class Jsontest{

    public static ArrayList<Subject> sub = new ArrayList<>();

    public static void main(String[] args) throws NullPointerException{

        String data = readFile();

        JSONArray JArray = new JSONArray(data);

        for(int n=0; n<JArray.length(); n++) {

            JSONObject Jobject = JArray.getJSONObject(n);

            String name = (String)Jobject.get("name");
            String day = (String)Jobject.get("day");
            float fperiod = Float.valueOf(Jobject.get("period").toString());
            int period = (int)fperiod;

            sub.add(new Subject(name , day, period));
        }

        PApplet.main("GUIbyP5");
    }

    public static class Subject{
        String name;
        int day;
        int period;

        Subject(String name,String day,int period){
            this.name = name;
            this.period = period;
            switch(day){
                case "Mon": this.day = 1; break;
                case "Tue": this.day = 2; break;
                case "Wed": this.day = 3; break;
                case "Thu": this.day = 4; break;
                case "Fri": this.day = 5; break;
            }
        }
    }

    private static String readFile(){
        try{
            File file = new File("src/TimeTable.json");
            BufferedReader br = new BufferedReader(new FileReader(file));

            String data = "";
            String str = br.readLine();
            while(str != null){
                data += str;
                str = br.readLine();
            }

            br.close();
            return data;
        }catch(FileNotFoundException e){
            System.out.println(e);
            return null;
        }catch(IOException e){
            System.out.println(e);
            return null;
        }
    }
}