Java composition - Constructor

Today I came across composition. From what I understand, for each instance of composition I need to create new object in constructor, like this :

public class Human {
   private String name;
   private Adress adress;

   public Human (String name, Adress adress) {
      this.name = name;
      this.adress = new Adress(adress);
   }
}

So if I would create a new instance of class human, I would need to assign to it some instance of adress, or create completely new adress, and the constructor would look like this

public class Human {
   private String name;
   private Adress adress;

   public Human (String name, String city, String country) {
      this.name = name;
      this.adress = new Adress(city, country);
   }
}

First of all, are those codes correct? And also is there any option, that if I would create new instance of class human, the atribute Adress would be empty, and I could set it later by using set method? Thank you very much for your response.

Solution

A new object is not mandatory in general, however, if you want to have the adress of human immutable (only if Adress is already not immutable), it is a good practice to kill all the references to it from outside the object.

That's indeed the rule for a composition.

This is naturally the way to do it, if adress takes an adress as input within its constructor.

public class Human {
    private String name;
    private Adress adress;

    public Human (String name, Adress adress) {
        this.name = name;
        this.adress = new Adress(adress); 
    }
}

If you want, you could have a set of different constructors and set some of the fields later

public class Human {
    private String name;
    private Adress adress;

    public Human() {}
    public Human(String name){
        this.name = name;
    }
    public Human(String name, Adress adress) {
        this.name = name;
        this.adress = adress; // or new Adress(adress)
    }

    public void setAdress (Adress adress) {
        this.adress = adress;
    }
}