android spinner不起作用。它没有选择

Question

我在片段中使用微调器。创建活动时，微调器不会显示任何内容。单击微调器时没有项目，但项目显示正确。 当我选择该项目时，即使我调用Toast消息也没有任何反应。

P.S。这些项来自数据库中String的ArrayList。

这是片段的代码：

public class RegStudentFragment extends Fragment {

    private Spinner uniSpinner;
    private RegistrationStudent activity;

    private ArrayList<String> listaUni;
    private int pos;

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.regs_frag, container, false);

        uniSpinner=(Spinner) view.findViewById(R.id.spinnerUni);
        System.out.println("fvfebeer");
        manageUSpinner();

        return view;
    }

    @Override
    public void onAttach(Activity activity) {
        super.onAttach(activity);
        this.activity = (RegistrationStudent) activity;
    }

    @Override
    public void onActivityCreated(Bundle savedInstancestate) {
        super.onActivityCreated(savedInstancestate);
        listaUni = new ArrayList<String>();

        new RequestFtp().setParameters(activity, "univer.php", "spinnerUni", RegStudentFragment.this).execute();

        ArrayAdapter<String> adapter = new ArrayAdapter<String>(this.getActivity().getApplicationContext(), android.R.layout.simple_spinner_item, getListaUni());
        adapter.setDropDownViewResource(android.R.layout.simple_dropdown_item_1line);

        uniSpinner.setAdapter(adapter);
        uniSpinner.setPrompt("Seleziona tra le seguenti:");

    }

    private void manageUSpinner() {
        uniSpinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
            @Override
            public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
                Toast.makeText(activity.getApplicationContext(),"you selected ",Toast.LENGTH_SHORT).show();
            }

            @Override
            public void onNothingSelected(AdapterView<?> parent) {
                Toast.makeText(activity.getApplicationContext(),"No select ",Toast.LENGTH_SHORT).show();
            }
        });

        System.out.println("vvsvsvsvsvs");
    }

    public void numeroel(ArrayList<ObjDb> result) {
        ObjDb res= result.get(0);
        String str=res.get("num");
        int num=Integer.parseInt(str);
        //numUni=new String[num];
    }

    public void arrayU(ArrayList<ObjDb> result){
        int i=0;
        while(i<result.size()) {
            ObjDb res = result.get(i);
            String str=res.get("nome");
            listaUni.add(str);
            i++;
        }
    }

    public ArrayList<String> getListaUni(){
        return listaUni;
    }

}