How can I identify 3 objects to read data from a file (Java)

Question

I want to read all the data from 3 object which all stay in the same Arraylist. For example, I have 3 classes which are Vehicle, Taxi, car. Taxi, car classes is inheritance from supclass Vehicle. Arraylist called vehiclelist contain taxi, car, vehicle. When I write object into a file, they got different properties. Here my Vehicle file

AAA232,23,TM,GG,222,123
ABC234,23,TA,ga,23,123,ATC
LMC232,23,TC,ga,23,123

The things is when I read these from Vehicle.txt back to an Arraylist. How can computer understand which one is belongs to Car or Taxi and if the Car have got 7 properties but the Taxi only have 6 properties, how can I solve it. Here my code, to read the file:

   static void readVehicleFile() {
        try {
            File f = new File("Vehicle.txt");
            Scanner SCF = new Scanner(f);

            while (SCF.hasNext()) {
                String record = SCF.nextLine();
                Scanner SCR = new Scanner(record);
                SCR.useDelimiter(",");

                String plateNum,model,make;
                int capacity,year,ownerID;

                plateNum = SCR.next();
                capacity = SCR.nextInt();
                make = SCR.next();
                model = SCR.next();
                year=SCR.nextInt();
                ownerID=SCR.nextInt();


                Vehicle vehicle = new Vehicle(plateNum,capacity,year,model,make,ownerID);
                vehicleList.add(vehicle);
            }
            SCF.close();
        } catch (FileNotFoundException e) {
            JOptionPane.showMessageDialog(null,"There is a error when saving file","Motor Vehicle Registration System",JOptionPane.ERROR_MESSAGE);

        }
    }  

As you can see, they all read by the vehicle not a car or taxi because if I use car object then vehicle cant not run because the vehicle only have 6 properties. Is there any solutions for it.