Question

I have several different type of Users (different classes) in my app

User1

User2

etc…

I want to have an abstract class “User” that joins the same methods for all type of Users
ex: getId(), getAge()....

I don’t really know how that works but what i want to do is something like :

User.setType(2); //a kind a constructor
User.getId()... //etc .. the getId() method of the Users2 class

Without having to instantiate the abstract class User

How can I do that ?
The problem I have is that an abstract class can’t have static methods … and User must be static or a Singleton I don’t know what is the best.

could anyone give me some tips ?

Thank you

Answer 1

public abstract class User {
    private int age;
    private int id;

    public int getAge() { return age; }
    public int getId() { return id; }
}


public class User1 extends User { }
public class User2 extends User { }

User user1 = new User1();
user1.getId();
User user2 = new User2();
user2.getId();

Without having to instantiate the abstract class User

Abstract classes cannot be instantiated.

User must be static or a Singleton I don’t know what is the best.

Even though abstract classes can have static methods, that does not quite make sense (specially when you want an abstract User and multiple specific types of Users).