Pass variable from Recyclerview-Holder to Mainactivity

Question

I tried a lot of things but I can't get it to work... I try to pass this String Variable (when i click Item in RecyclerView) to my MainActivity. What works bad is calling the function (OnRecyclerViewItemClick) and changing the variable(GetUrlFromItem). My version of Android Studio is 2.3.3

I really need do this:

My RecyclerView:

public class viewHolder extends RecyclerView.ViewHolder implements View.OnClickListener{

    TextView titulo;
    Button playbtn01;
    List<Fuente> ListaObjeto;

    public viewHolder(View itemView,List<Fuente> datos) {
        super(itemView);

        ListaObjeto = datos;

        titulo = (TextView) itemView.findViewById(R.id.texto);
        playbtn01 = (Button) itemView.findViewById(R.id.playbtn00);

        playbtn01.setOnClickListener(this);
    }

    @Override
    public void onClick(View view) {
        int position = getAdapterPosition();
        Fuente objeto = ListaObjeto.get(position);

        if (view.getId() == playbtn01.getId()) {

            MainActivity mainActivity = new MainActivity:
            mainActivity.OnRecyclerViewItemClick();      /// initiate Void in Main
            mainActivity.GetUrlFromItem = objeto.GetUrl; //Change Variable of Main

        }
    }
}

MainActivity

public class MainActivity extends AppCompatActivity {

    public String GetUrlFromItem; 

    public void OnRecyclerViewItemClick() {
        if (GetUrlFromItem  == "..."){
            doSomething...
        }
    }
}

Answer 1

There are two big problems that I see.

The first is how you get a MainActivity instance to work with. In your question, you have this line of code:

MainActivity mainActivity = new MainActivity:

Calling new is going to do exactly what it sounds like: create a new instance of the MainActivity class. You do not want a new instance! You want your alive and running instance.

There are a handful of ways to get ahold of your alive and running MainActivity , but probably the simplest one for now is going to be casting your ViewHolder 's itemView 's Context . So instead of the above, write something like this:

MainActivity mainActivity = (MainActivity) itemView.getContext();

The second big problem is in the next two lines:

mainActivity.OnRecyclerViewItemClick();
mainActivity.GetUrlFromItem = objeto.GetUrl;

The problem here is the order of these two statements. Because you invoke mainActivity.OnRecyclerViewItemClick() before setting the value of mainActivity.GetUrlFromItem , the value will not be updated when OnRecyclerViewItemClick() is executed.

Simply swap the order of these two lines.