JAVA-关于ArrayList

Question

Hi i have a question about ArrayList in Java.

I have in a class called "Utente" an ArrayList ricFriends; Now, the problem is that i have a method called

requestFriendship(Utente u) 

where i want to add in the u.ricFriends the object Utente that call the method...

I tried in this way but it's at 99% wrong..

public void requestFriendship(Utente u){
    u.ricFriends.add(this);
}

for example i want to do this :

Utente Gary = new Utente();
Utente Mike = new Utente();

Gary.requestFriendship(Mike);

And if i check Mike.ricFriends i can see the object Gary;

Sorry for the english, thank you.

Answer 1

Not sure what you're trying to do, but you should change this line:

 u.ricFriends.add(this);

for this:

  this.ricFriends.add(u)

Answer 2

First of all, you are making a attribute public, that's not a good practice in OO programming, you should create get and set methods.

About you problem, you could do it something like this:

ArrayList<Utente> utenteList = u.getRicFriends();

utenteList.add(Mike);

Take care about "this" pointer, "this" mean that you are taking the object reference himself.