Java Constructor and Inheritance, how to do it?

[severe sinew]

Hello,
I was trying to create the parent class Person. This is my constructor:
```public Person(String name, String fname, String street, Integer hnumber, String city, Integer zip, String mail, String student, int mnumber ){
this.nachname = name;
this.vorname = fname;
this.straße = street;
this.hausnummer = hnumber;
this.stadt = city;
this.plz = zip;
this.mail = mail;
this.student = student;
this.mnumber =mnumber;

}```

now I have a second class called students and I want that Student inherit from Person. Is this the correct way to do it?

public class Student extends Person{
public Student(String name, String fname, String street, Integer hnumber, String city, Integer zip, String mail, String student, int mnumber )
    {
        super(name, fname, street, hnumber, city, zip, mail, student, mnumber);
    }}```

[winter raptor]

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[fierce otter]

I guess, though with that number of parameters it could be understandable to leave a lot of them to setters instead, unless your classes are immutable

[severe sinew]

thanks for the anwser but what is a setter?

[winter raptor]

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[fierce otter]

A method, like setStreet(String street) in charge of setting the value of one field

[visual terrace]

You should read about setters and getters if you are working with classes. They help in extracting values from a variable and change it especially if the data members are private.

[errant wagon]

see the classes and objects article here:

[winter raptor]

https://dev.java/learn

[errant wagon]

@severe sinew ^

[severe sinew]

Thanks yes but in this class i dont need setters, because i dont want to retrun a value. My question would be, how can i built a constructor which inheriate the attributes from a instance of a class?

[winter raptor]

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[visual terrace]

Not clear with the question. A class inherits things. In a method it constructor, you can use the object of any class to access variables and methods of it.

[severe sinew]

but i want to do something like this. I want that Student inherits its attribute values like this.name from an instance and not a class. For example i created an instance x of Person with the name Foo, now i want to give this instance as input that Student get the same name.

[midnight warren]

then you can simply create a constructor that accepts a variable of type Person

[severe sinew]

yes do you mean something like this constructor ->:

super()
}```
but i dont now what to write inside the super method in the constructor 😦

[midnight warren]

but i dont now what to write inside the super method in the constructor 😦
so you don't want to do:

public Student (Person x){
  super(x);
}

?

[midnight warren]

why not ?

[severe sinew]

This is what i want to archieve

but i get a Syntax Error

[midnight warren]

let me guess. Your Person class doesn't have a constructor which just defines a single Person object ?

[severe sinew]

it says requiered type String provided Oerson

[severe sinew]

no it has one

[midnight warren]

show me

[severe sinew]

        this.nachname = nachname;
        this.vorname = vorname;
        this.straße = straße;
        this.hausnummer = hausnummer;
        this.stadt = stadt;
        this.plz = plz;
        this.mail = mail;
        this.student = student;

    }```

[midnight warren]

I meant a Person constructor like this:

public Person(Person person) {
    //Initialise Person object
}

[severe sinew]

In which class?

[midnight warren]

in the Person class

[severe sinew]

but i dont have a person to pass, because I ve to pass it a name, fname and other Attributes.

[midnight warren]

so you don't have an instance of Person that you can pass to the Student constructor ?

[severe sinew]

in my main class i created an instance of Person with the constructor above, but i cant pass the instance.

to the constructor in the student class

[midnight warren]

yeah then create the two constructors I just showed you. One constructor for Student which accepts an instance of Person and in the Person class you create a constructor which just accepts another instance of Person

[severe sinew]

Okay thanks but will I get then 2 instances of Person in my main class?

[winter raptor]

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[midnight warren]

no you pass the Person object to the contructor of the Student class. This will create a new instance of Student.

you cann assign that Student object to a Person variable again but it will still be of type Student

[severe sinew]

And this will stay empty?
public Person( Person person){}

But i created the first instance of person with the first constructor, then i pass this instance to create a new instance of Person, right? And that i will pass to Student. Did i understand it correct?

[midnight warren]

this won't stay empty. You will have to create another Person object. If that's what you meant then yes, you will create a new instance of Person

[severe sinew]

Okay but what do i ve to write in the body?

[midnight warren]

whatever you need to do to get the Person instance to a default state. Popluate class fields, maybe some logic. Or just call another constructor with its respective args.

[severe sinew]

So something like this.name = person.name

?

[midnight warren]

yeah or you do something like:
this(person.name,person.fname,...) and so on.

[severe sinew]

Ahh this is mindblowing for me rn. Okay but how do i handle private Attributes

With getMethods?

[errant wagon]

with getters yeah

[severe sinew]

Im really thankful to you all, I will try to implement it now.

[winter raptor]

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