如何從此片段中的onItemSelectedListener中獲取微調器單擊的項目？

Question

我有以下代碼。我希望onItemSelectedListener將所選字符串的值放入store_id以供進一步處理。我使用Toast來檢查它，因爲我無法將監視放在監聽器上，而store_id是默認爲空。微調員顯示我的各種字符串，但點擊時消失。有任何想法嗎？我不能想象我的問題是具有在該片段在一起的所有代碼... output right before clicking on a store

public class ChooseStoreFragment extends Fragment implements AdapterView.OnItemSelectedListener { 
ArrayList<String> store_array = new ArrayList<>(); 
String store_id; 

//implementing the AdapterView.OnItemSelectedListener 
@Override 
public void onItemSelected(AdapterView<?> parent, View view, int position, long id) { 
    String user_store_id = parent.getItemAtPosition(position).toString();//doesn't show up in toast 
    store_id = parent.getSelectedItem().toString();//doesn't show up in toast 
    Toast.makeText(getActivity(), user_store_id + "=user_store_id.", Toast.LENGTH_SHORT).show(); 
} 

@Override 
public void onNothingSelected(AdapterView<?> parent) { 
    Toast.makeText(parent.getContext(),"Nothing selected",Toast.LENGTH_SHORT).show(); 
} 

@Override 
public View onCreateView(LayoutInflater inflater, ViewGroup container, 
         Bundle savedInstanceState) { 
    final View thisView = inflater.inflate(fragment_choose_store, container, false); 
    final Spinner spinner = (Spinner) thisView.findViewById(R.id.stores_spinner); 
    ArrayAdapter<String> adapter = new ArrayAdapter<>(this.getContext(),android.R.layout.simple_spinner_dropdown_item,store_array); 
    spinner.setAdapter(adapter); 
    AdapterView.OnItemSelectedListener mListener = new AdapterView.OnItemSelectedListener() { 
     @Override 
     public void onItemSelected(AdapterView<?> parent, View view, int position, long id) { 
      store_id = parent.getSelectedItem().toString(); 
     } //still never shows up in toast 

     @Override 
     public void onNothingSelected(AdapterView<?> parent) { 
      Toast.makeText(getActivity(), "none found = user_store_id.", Toast.LENGTH_SHORT).show(); //still nothing 
     } 
    }; 
    spinner.setOnItemSelectedListener(mListener); 

Answer 1

您已經註冊了一個偵聽器spinner，所以你不必做ChooseStoreFragment執行該listener再次。

spinner.setOnItemSelectedListener(mListener); 

它應該是這樣的

public class ChooseStoreFragment extends Fragment { 
    ArrayList<String> store_array = new ArrayList<>(); 
    String store_id; 

    @Override 
    public View onCreateView(LayoutInflater inflater, ViewGroup container, 
          Bundle savedInstanceState) { 
     final View thisView = inflater.inflate(fragment_choose_store, container, false); 
     final Spinner spinner = (Spinner) thisView.findViewById(R.id.stores_spinner); 
     ArrayAdapter<String> adapter = new ArrayAdapter<>(this.getContext(), android.R.layout.simple_spinner_dropdown_item, store_array); 
     spinner.setAdapter(adapter); 
     AdapterView.OnItemSelectedListener mListener = new AdapterView.OnItemSelectedListener() { 
      @Override 
      public void onItemSelected(AdapterView<?> parent, View view, int position, long id) { 
       store_id = parent.getSelectedItem().toString(); 
      } //still never shows up in toast 

      @Override 
      public void onNothingSelected(AdapterView<?> parent) { 
       Toast.makeText(getActivity(), "none found = user_store_id.", Toast.LENGTH_SHORT).show(); //still nothing 
      } 
     }; 
     spinner.setOnItemSelectedListener(mListener); // Register this spinner for a mListener 
    } 
} 

或者，如果你想爲你的類

public class ChooseStoreFragment extends Fragment implements AdapterView.OnItemSelectedListener { 
    ArrayList<String> store_array = new ArrayList<>(); 
    String store_id; 

    //implementing the AdapterView.OnItemSelectedListener 
    @Override 
    public void onItemSelected(AdapterView<?> parent, View view, int position, long id) { 
     String user_store_id = parent.getItemAtPosition(position).toString();//doesn't show up in toast 
     store_id = parent.getSelectedItem().toString();//doesn't show up in toast 
     Toast.makeText(getActivity(), user_store_id + "=user_store_id.", Toast.LENGTH_SHORT).show(); 
    } 

    @Override 
    public void onNothingSelected(AdapterView<?> parent) { 
     Toast.makeText(parent.getContext(), "Nothing selected", Toast.LENGTH_SHORT).show(); 
    } 

    @Override 
    public View onCreateView(LayoutInflater inflater, ViewGroup container, 
          Bundle savedInstanceState) { 
     final View thisView = inflater.inflate(fragment_choose_store, container, false); 
     final Spinner spinner = (Spinner) thisView.findViewById(R.id.stores_spinner); 
     ArrayAdapter<String> adapter = new ArrayAdapter<>(this.getContext(), android.R.layout.simple_spinner_dropdown_item, store_array); 
     spinner.setAdapter(adapter); 
     spinner.setOnItemSelectedListener(this);// register this fragment with a listener 
    } 
} 

註冊登記監聽器只有1聽衆！

更新：

public class ChooseStoreFragment extends Fragment implements AdapterView.OnItemSelectedListener { 
    ArrayList<String> store_array = new ArrayList<>(); 
    String store_id; 

    //implementing the AdapterView.OnItemSelectedListener 
    @Override 
    public void onItemSelected(AdapterView<?> parent, View view, int position, long id) { 
     String user_store_id = store_array.get(position); 
     Toast.makeText(getActivity(), user_store_id, Toast.LENGTH_SHORT).show(); 
    } 

    @Override 
    public void onNothingSelected(AdapterView<?> parent) { 
     Toast.makeText(getActivity(), "Nothing selected", Toast.LENGTH_SHORT).show(); 
    } 

    @Override 
    public View onCreateView(LayoutInflater inflater, ViewGroup container, 
          Bundle savedInstanceState) { 
     final View thisView = inflater.inflate(R.layout.fragment_choose_store, container, false); 
     final Spinner spinner = (Spinner) thisView.findViewById(R.id.stores_spinner); 
     ArrayAdapter<String> adapter = new ArrayAdapter<>(this.getActivity(), android.R.layout.simple_spinner_dropdown_item, store_array); 
     spinner.setAdapter(adapter); 
     spinner.setOnItemSelectedListener(this);// register this fragment with a listener 
     return thisView; 
    } 
}