How do I loop / can I loop a hashmap put()?

Question

I have an Arraylist with Vehicle properties and I needed to store them in a "car park slot", so I have decided to use HashMap to store vehicle slot with the vehicle registration, for example "1 = VEHICLE".

In my code I have it so that it adds an Integer and a Vehicle with a put statement after getting the required information from user input, it works for the first input but then after that it just gets replaced, how would I go about looping the put() or making a loop to add stuff into the map?

(I am also planning on making my HashMap creation and population a function that I call instead, this is just a temp thing until I figure this out or realise it's not possible.)

   public void carInfo(Vehicle tempVehicle, parkingSpace vehicle) {

        HashMap<Integer, Vehicle> hash_map = new HashMap<Integer, Vehicle>();

        array = new MCP();

        System.out.println("Please enter number plate: ");
        input = new Scanner(System.in);
        String plate = input.nextLine();

        System.out.println("Please enter car make: ");
        input = new Scanner(System.in);
        String make = input.nextLine();

        System.out.println("How would you best describe your Vehicle? ");
        System.out.println("(Car, Small Van, Tall Van, Long Van, Coach, Motorbike)");
        type = new Scanner(System.in);
        String type1 = input.nextLine();

            if (type1.equalsIgnoreCase(vehicleType.CAR.toString())) {
                tempVehicle.setPlate(plate);
                tempVehicle.setCarMake(make);
                tempVehicle.setVehicle(vehicleType.CAR);
                inv.createInvoice();
                tempVehicle.setInvoiceNumber(inv.invoiceNumber);

                array.addStandard(tempVehicle);

                hash_map.put(test++, tempVehicle);

                System.out.println(hash_map.toString());

I expect to add many inputs and get something like:

1 = Vehicle

2 = Vehicle

Instead I just get

1 = Vehicle

and then it will replace the first vehicle and then give out

2 = Vehicle

I have researched and realised it's because I only have 1 put so it just replaces the current thing mapped there, i'm just not sure how to loop it to fix this.

Answer 1

每次调用 carInfo 方法时都会创建一个新的 HashMap，因此 HashMap 始终只有一个条目，您可以将 HashMap 作为类的局部变量来解决这个问题。