RXJava, Log not retrived onNext

[Giovanni Montano]

Dear All, as spoken in Java beginner, will ask here my question as there is not an RXJava forum, Android does not treat advanced features, and RXJava is really similar to Stream

I am using retrofit2 a popular Jake Wharton library from square that simplify the access to the REST API
in the breakpoint I see that it is retrieved in OnNext  a StackoverflowAPI response with 30 data.
but I can neither loop trough the array, nor even send simple messages

Please consider that in Android Log.d is similar to systemoutplrintln

package com.vogella.android.retrofitstackoverflow;

import (..)
public class MainActivity extends ListActivity {


    //original https://api.stackexchange.com/2.2/search?order=desc&sort=activity&tagged=android&site=stackoverflow

    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        requestWindowFeature(Window.FEATURE_INDETERMINATE_PROGRESS);
        requestWindowFeature(Window.FEATURE_PROGRESS);
        ArrayAdapter<Question> arrayAdapter =
                new ArrayAdapter<Question>(this,
                        android.R.layout.simple_list_item_1,
                        android.R.id.text1,
                        new ArrayList<Question>());
        setListAdapter(arrayAdapter);
        setProgressBarIndeterminateVisibility(true);
        setProgressBarVisibility(true);
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.main_menu, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        setProgressBarIndeterminateVisibility(true);
        Gson gson = new GsonBuilder()
                .setDateFormat("yyyy-MM-dd'T'HH:mm:ssZ")
                .create();
        Retrofit retrofit = new Retrofit.Builder()
                .baseUrl("https://api.stackexchange.com")
                .addCallAdapterFactory(RxJavaCallAdapterFactory.create())
                .addConverterFactory(GsonConverterFactory.create(gson))
                .build();

        // prepare call in Retrofit 2.0
        StackOverflowAPI stackOverflowAPI = retrofit.create(StackOverflowAPI.class);


        //the real call to the server
        //Call<StackOverflowQuestions> call = stackOverflowAPI.loadQuestions("android");


        Observable<StackOverflowQuestions> observable = stackOverflowAPI.loadQuestions("android");

        observable.observeOn(AndroidSchedulers.mainThread())
                .subscribeOn(Schedulers.io())
                .subscribe(new Subscriber<StackOverflowQuestions>() {
                    @Override
                    public void onCompleted() {
                        Log.d("IVO", "completed");
                    }

                    @Override
                    public void onError(Throwable e) {

                    }

                    @Override
                    public void onNext(StackOverflowQuestions stackOverflowQuestions) {

                        Log.d("IVO", "onNext" + stackOverflowQuestions.items.get(1).title.toString());
                        Log.d("IVO", "onNext" );


        return true;
    }


}

and

import java.util.List;

public class StackOverflowQuestions {
    List<Question> items;
}

and last

// This is used to map the JSON keys to the object by GSON
public class Question {

    String title;
    String link;

    @Override
    public String toString() {
        return(title);
    }
}