Java Convert from .bin file to .txt loading

Question

How would I go about changing this from loading .bin to .txt. I would like the information on the .txt file be put into the hashmap just like .bin file.

    public static int currency;
    public HashMap<Integer, Shop> cars = new HashMap<Integer, Car>();    
public void load() {
            try {
                @SuppressWarnings("resource")
                RandomAccessFile carFile = new RandomAccessFile("data/cars.bin", "r");
                int carsAmt = carFile.readShort();
                for (int carId = 0; carId < carAmt; carId++) {
                    int carId = carFile.readShort();
                    int currency = carFile.readShort();
                    int[] cars = new int[carFile.readByte()];
                    int[] amounts = new int[cars.length];
                    boolean isTruck = carFile.read() == 1;
                    for (int carData = 0; carData < cars.length; carData++) {
                        cars[carData] = carFile.readShort();
                        amounts[carData] = carFile.readInt();
                    }
                    cars.put(carId, new Car(carId, currency, isTruck, cars, amounts, true));
                }
            } catch (FileNotFoundException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            }
            System.out.println("Loaded " + cars.size() + " Cars");
        }

Answer 1

bin and txt are just parts of the name. However, by convention, a txt file contains data formatted using one of many character encodings . Common encodings are UTF-8 and the extensions of ASCII. An "encoding" is just a mapping of a sequence of bytes to a character. For example, in UTF-8, a maps to the 8 bit sequence 01100001 ( 61 in hexadecimal). Realistically, all files are stored as a series of 0 s and 1 s, but txt files usually only store sequences according to their encoding. By contrast, a bin file would contain data stored in a "binary" format; that is, the data in them does not match any kind of text encoding. In your case, the bin file just contains a set of numbers stored as their binary representations (which is a sequence of bits or 0s and 1s).

The answer to your question is that you're going to have to rewrite this block of code. Since you now want to read a text file instead of using the binary values directly, you'll need a reader that can decode your txt file into String s, and then you'll also need to turn those String s into numeric values. (This step is called "parsing".)

You will need to know the encoding of your txt file to be able to read it correctly. RandomAccessFile has a method to read UTF-8 encoding text, but if it's in another encoding, you'll need to look elsewhere. See this answer for some information on using BufferedReader . You may also find the Scanner class useful. Scanner can parse the values for you as it reads them in.