在另一个 class 中使用 object

Question

I want to use the object person in the Librarian_Interface class, but this call the method login() in a loop. I think there is something I don't understand with java instance and I tried to get person with a constructor or methode but in vain. Thanks !

public class Login_Interface {
    Person person;

    public Login_Interface() {
        
        db.initConnection();
        person = login(db, in);
        
        if (person != null)
        {
            Librarian_Interface a = new Librarian_Interface();
            a.run();
        }
    }

    public void run() {
    }

    public static Person login(DbConnection db, Scanner sc) {
        Persons.setDbConnection(db);
        Persons persons = Persons.getInstance();

        System.out.print("\nEnter your Phone Number : ");
        String phone = sc.nextLine();

        System.out.print("\nEnter your Password : ");
        String password = sc.nextLine();

        return persons.login(phone, password);
    }

}

public class Librarian_Interface {

public Librarian_Interface() {

// What I want 
// System.out.print(person); or person.getAge(); ...

Answer 1

All you have to do is pass the person object to the Librarian_Interface constructor. then you can call methods getAge on it, etc.

public class Librarian implements Runnable {

    private final Person person;

    public Librarian(Person person) {
        this.person = person;
    }

    @Override
    public void run() {
        int age = person.age();
        // ... whatever else
    }
}

By the way, the convention in Java is to use upper camel case for class names, with no underscores. So it would be better to name the class LibrarianInterface . Also, it's probably not the best idea to call it LibrarianInterface if it is in fact a class and not an interface .

Since Librarian has a public run method, it's a good idea to have it implement Runnable so that users of the class see how it is meant to be used.