Thread: Reading in data from a text file and adding to ArrayList

I need to read in data from a text file with a scanner, which contains a list of vehicles. I'm then adding these Vehicles to an ArrayList. Each we have separate subclasses already written for a Car, Bike, raceCar, and Vehicle class. Each vehicle type is identified by a single char. (ex. raceCar 'R', Bike 'B' etc). So if I'm scanning from the file and I reach an 'R' that means that I have to scan the next 5 lines following it for (Make, Model, numWheels, engineSize, raceType). However, if I scan char 'C' or 'B' i'll have to read only the next 4.

I keep getting this error:

Exception in thread "main" java.lang.StringIndexOutOfBoundsException: String index out of range: 0
at java.lang.String.charAt(String.java:658)
at VehicleDriver.inputVehicles(VehicleDriver.java:18)
at VehicleDriver.main(VehicleDriver.java:9)


--------------------------
From here i'm not sure what i'm supposed to do. And honestly i'm not even sure if this code I have will work and preform the necessary task. Any tips on what I could do?

import java.util.*;
import java.io.*;//File
public class VehicleDriver 
{
   public static void main (String [] args)throws IOException
   {
      ArrayList <Vehicle> vehicles = new ArrayList<Vehicle> ();
 
      inputVehicles(vehicles);
 
    }//end main()
 
    public static void inputVehicles(ArrayList<Vehicle> vehicles)throws IOException
     {    
         File infile = new File("vehicles.txt");  
         Scanner scan = new Scanner(infile);
         String x = "";
         char c = x.charAt(0);
 
         String make = "";
         String model = "";
         int numWheels = 0;
         int numGears = 0;
         String engineSize = "";
         String raceType = "";
 
 
 
         if(!infile.exists())
         {
            System.out.println("Your file does not exist");
            System.exit(0);
         }//end if
 
         while(scan.hasNext())
         {
 
             if(c == 'R')
             {
                make = scan.nextLine();
                model = scan.nextLine();
                numWheels = scan.nextInt();
                engineSize = scan.nextLine();
                raceType = scan.nextLine();
 
                RaceCar rc = new RaceCar(make, model, numWheels, engineSize, raceType);
                vehicles.add(rc);
                System.out.println(rc);
 
             }  
             else if(c == 'B') 
             {
                make = scan.nextLine();
                model = scan.nextLine();
                numWheels = scan.nextInt();
                numGears = scan.nextInt();
 
                Bike bi = new Bike(make, model, numWheels, numGears);
                vehicles.add(bi);
                System.out.println(bi);
             }
             else if(c == 'C')
             {
                make = scan.nextLine();
                model = scan.nextLine();
                numWheels = scan.nextInt();
                engineSize = scan.nextLine();
 
                Car ca = new Car(make, model, numWheels, engineSize);
                vehicles.add(ca);
                System.out.println(ca);
             }
 
 
         }//end forloop
           scan.close();
   }//end inputVehicles
 
}//end class

Below is the textfile

R
Dodge
Charger
4
5.7L
Nascar
C
Volkswagon
Taureg
4
V6
B
Schwinn
Super Deluxe
2
2
R
Aston Martin
DB9
4
6.0L
Le Mans
B
Cannondale
Trigger 29 3
2
30
C
Ford
Focus
4
2.0L

Vehicle Class

public class Vehicle 
{
   private String make;
   private String model;
   protected int numWheels;
 
   public Vehicle()
   {
      make = model = "";
      numWheels = 0;
   }//end default 
 
   public Vehicle(String make, String model, int numWheels)
   {
      this.make = make;
      this.model = model;
      this.numWheels = numWheels;
   }//end 2nd constructor
 
   public String getMake()
   {
      return make;
   }//end getMake()
 
   public String getModel()
   {
      return model;
   }//end getModel()
 
   public int getNumWheels()
   {
      return numWheels;
   }//end getNumWheels()
 
   //setters go here
 
   public String toString()
   {
      return "Make: " + make + 
             "\nModel: " + model +
             "\nNumber of Wheels: " + numWheels;
   }//end toString()
}//end class Vehicle

Car Class

public class Car extends Vehicle
{
   private String engineSize;
 
   public Car()
   {
      super();
      engineSize = "";
   }//end super constructor
 
   public Car(String make, String model, int numWheels, String engineSize)
   {
      super(make, model, numWheels);
      this.engineSize = engineSize;
   }
 
   public String getEngineSize()
   {
      return engineSize;
   }
 
   public String toString()
   {
      String str = "";
      str += super.toString();
      str += "\nEngine size: " + engineSize;
      return str;
   }
}

RaceCar Class

public class RaceCar extends Car
{
   private String raceType;
 
   public RaceCar()
   {
      super();//default constructor of Car
      raceType = "";
   }//end super constructor
 
   public RaceCar(String make, String model, int numWheels, String engineSize, String raceType)
   {
      super(make, model, numWheels, engineSize);
      this.raceType = raceType;
   }//end 2nd constructor
 
   public String getRaceType()
   {
      return raceType;
   }
 
   public String toString()
   {
      String str = "";
      str += super.toString();
      str += "\nRace Type: " + raceType;
      return str;
   }
}

Bike Class

public class Bike extends Vehicle
{
   private int numGears;
 
   public Bike()
   {
      super();
      numGears = 0;
   }//end super constructor
 
   public Bike(String make, String model, int numWheels, int numGears)
   {
      super(make, model, numWheels);
      this.numGears = numGears;
   }
 
   public int getNumGears()
   {
      return numGears;
   }//end getNumGears()
 
   public String toString()
   {
      String str = "";
      str += super.toString();
      str += "\nNumber Of Gears: " + numGears;
      return str;
   }
}

I'm honestly pretty lost and I don't know how to do that.

look at this statement in your code in VehiclDriver program:

File infile = new File("vehicles.txt");
Scanner scan = new Scanner(infile);
String x = "";
char c = x.charAt(0);

you are trying to access the first character in your String x, but actually String x is empty. that is why it throws an Exception of Array index out of bounds. there is no element in your String x so how could you get a character from it?

I reassigned String x which was empty to char c = x.CharAt(0). String x was empty on line 17, when I first made it.

I'm not even asking for the length though? I don't see how that's relevant.

We had written(my classmates and our instructor) had written everything aside from the Bike class, and we had written a different vehicleDriver.

We have just gotten into Arrays and ArrayLists about a week ago. And this is our first time adding to an ArrayList.

I honestly don't know. I figured that was creating a char called c, and then assigning it to x.charAt(0). I had made x empty because I don't know what else to set it to. I understand what you're saying with why is throws and exception of array index out of bounds. But I don't know how to fix that. I need to start reading the from the file find that the first letter is either 'R' or 'B' or 'C'. Then read a certain amount of lines after that depending on which I read in.

I'd like to think that i'm somewhat close to a solution, but I have honestly no idea. I've never done anything like this before, and I have nothing I can compare it too.

I honestly have no clue. Thanks for trying to help, but the headache isn't worth it. I'll turn the assignment in as it is.

I'll make this as solved.

Thanks you.