Java auto increment from base

Question

In my case I have class and subclass. Problem is when I search my function increment id automatically. When I first time click search it upload 5 ids, when I add one and go back to search it upload 5 ids I have + (5 old + 1 new). Then if I want to add new one it gives him id 5+6 + 1 new = 13 id.

Class auto long has id and name:

    public static AtomicInteger idSequence = new AtomicInteger();

    public Car(String name) {
        this.id = (long)idSequence.incrementAndGet();
        this.name= name;
    }

Subclass:

 public OldCars(String name){
        super(name);
    }

Function to update from H2:

  public static List<Car> uploadAllCars() throws SQLException, IOException {
        Connection connection= connectToDatabase();
        List<Car> listOfCars= new ArrayList<>();

    Statement stmt = connection.createStatement();
    ResultSet rs = stmt.executeQuery("SELECT * FROM CARS");

    while(rs.next()){
        Long id = rs.getLong("id");
        String name= rs.getString("name");
     
        Car car= new Car(name);
        car.setId(id);
        listOfCars.add(car);

    }
    closeConnectionToDataBase(connection);

    return listOfCars;}

Problem is how to stop auto increment and call function without sum of ids. I'm calling uploadAllCars function to search every time specific car but it auto increment instantly.

Edit: I want from user to input name (not id)

By the way, we usually let the database engine manage incrementing a serial number and assigning it to each new row. That chore is one of the specialties of a database engine. No need for you to mange the `AtomicInteger` and such. The engine is likely to do a better job than you or me. And the ID generation would be invoked universally if you are using tools and apps other than this particular Java app. If you need the newly generated IDs, JDBC provides a facility for you to request them. — Basil Bourque, Apr 25 '21 at 23:49

Jakub Dóka · Answer 1 · 2021-04-24T10:48:44.643

1

define another constructor for getting cars from database like this:

public Car(String name, long id) {
        this.id = id;
        this.name = name;
}

and use that instead of new Car(name), so new Car(name, id)

edited Apr 24 '21 at 10:48

answered Apr 24 '21 at 10:48

Jakub Dóka

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I don't want user to input it – None4 Apr 24 '21 at 10:48
than make it a private constructor – Jakub Dóka Apr 24 '21 at 10:49
I want from user to input name not id – None4 Apr 24 '21 at 10:52
user can use a cunstructor with only the name while you can use that with id as you need. Its called constructor owerloading. – Jakub Dóka Apr 24 '21 at 10:56
But my subclasses extends class Car – None4 Apr 24 '21 at 11:02
And why does that matter? – Jakub Dóka Apr 24 '21 at 11:05
How they will inherit private constructor – None4 Apr 24 '21 at 11:13
then make it protected – Jakub Dóka Apr 24 '21 at 11:16
what will I get with that I only need id of super class or maybe I should make id in every subclass and then use it – None4 Apr 24 '21 at 12:40
@None4 Adding a second identifier to a subclass would be senseless if you already have one in the superclass. – Basil Bourque Apr 25 '21 at 23:43

Java auto increment from base

1 Answers1