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我尝试了很多方法在我的片段视图中成功地使用onitemselectedlistener，但不断得到一个致命异常java.lang.NullPointerException，并且它始终指向代码中用于设置onitemselectedlistener的同一行旋转器的方法。Android onitemselectedlistener在片段中抛出空指针异常
机器人工作室logcat的误差输出为：
07-21 13：55：06.544 17277-17277/com.vaibhavtech.indoreveg E/AndroidRuntime：致命异常：主要过程： com.vaibhavtech。 indoreveg，PID：17277
显示java.lang.NullPointerException 在com.vaibhavtech.indoreveg.activity.VegetablesFragment.onCreateView（VegetablesFragment.java:91） 在android.support.v4.app.Fragment.performCreateView（Fragment.java： 1786） at android.support.v4.app.FragmentManagerImpl.moveToState（FragmentManager.java:953） at android.support.v4.app.FragmentManagerImpl.moveToState（FragmentManager.java:1136） at android.support.v4.app.BackStackRecord.run（BackStackRecord.java:739） at android.support.v4.app。 FragmentManagerImpl.execPendingActions（FragmentManager.java:1499） at android.support.v4.app.FragmentManagerImpl $ 1.run（FragmentManager.java:456） at android.os.Handler.handleCallback（Handler.java:808） at android .os.Handler.dispatchMessage（Handler.java:103） at android.os.Looper.loop（Looper.java:193） at android.app.ActivityThread.main（ActivityThread.java:5395） at java.lang .reflect.Method.invokeNative（Native Method） at java.lang.reflect.Method.invoke（Method.java:515） at com.android.internal.os.ZygoteInit $ MethodAndArgsCaller.run（ZygoteInit.java:837） at com.android.internal.os.ZygoteInit.main（ZygoteInit.java:653）at dalvik.system.NativeStart。主（本地方法）
片段类：
public class VegetablesFragment extends Fragment {
// Log tag
private static final String TAG = MainActivity.class.getSimpleName();
private Spinner spinnerPacking;
// array list for spinner adapter
private ArrayList<Packing> spinnerList;
// Product json url
private static final String url = "http://www.indoreveg.com/androidapi1/products.php?category=vegetable";
private ProgressDialog pDialog;
private List<Products> productsList = new ArrayList<Products>();
private ListView listView;
private CustomListAdapter adapter;
public VegetablesFragment() {
// Required empty public constructor
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
// Inflate the layout for this fragment
View layout = inflater.inflate(R.layout.fragment_vegetables, container, false);
listView = (ListView) layout.findViewById(R.id.list);
spinnerPacking = (Spinner) layout.findViewById(R.id.packingList);
spinnerList = new ArrayList<Packing>();
/* spinner item select listener */
spinnerPacking.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
@Override
public void onItemSelected(AdapterView<?> arg0, View arg1,
int arg2, long arg3) {
// TODO Auto-generated method stub
String msupplier=spinnerPacking.getSelectedItem().toString();
Log.e("Selected item : ",msupplier);
}
@Override
public void onNothingSelected(AdapterView<?> arg0) {
// TODO Auto-generated method stub
}
});
adapter = new CustomListAdapter(getActivity(), productsList);
listView.setAdapter(adapter);
pDialog = new ProgressDialog(getActivity());
// Showing progress dialog before making http request
pDialog.setMessage("Loading...");
pDialog.show();
populateSpinner();
// Creating volley request obj
JsonArrayRequest productsReq = new JsonArrayRequest(url, new Response.Listener<JSONArray>() {
@Override
public void onResponse(JSONArray response) {
Log.d(TAG, response.toString());
hidePDialog();
// Parsing json
for (int i = 0; i < response.length(); i++) {
try {
JSONObject obj = response.getJSONObject(i);
Products products = new Products();
products.setTitle(obj.getString("name"));
products.setThumbnailUrl(obj.getString("image"));
products.setOurPrice(obj.getString("our_price"));
products.setMarketPrice(obj.getString("market_price"));
// Packing is json array
JSONArray packingArry = obj.getJSONArray("packing");
ArrayList<String> packings = new ArrayList<String>();
for (int j = 0; j < packingArry.length(); j++) {
packings.add((String) packingArry.get(j));
}
products.setPacking(packings);
// adding products to products array
productsList.add(products);
JSONArray mpackingArray = obj.getJSONArray("packing");
for (int m = 0; m < mpackingArray.length(); m++) {
JSONObject packObj = (JSONObject) mpackingArray.get(m);
Packing pack = new Packing(packObj.getString("pack"));
spinnerList.add(pack);
}
} catch (JSONException e) {
e.printStackTrace();
}
}
// notifying list adapter about data changes
// so that it renders the list view with updated data
adapter.notifyDataSetChanged();
}
}, new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
VolleyLog.d(TAG, "Error: " + error.getMessage());
hidePDialog();
}
});
// Adding request to request queue
AppController.getInstance().addToRequestQueue(productsReq);
return layout;
}
@Override
public void onDestroy() {
super.onDestroy();
hidePDialog();
}
private void hidePDialog() {
if (pDialog != null) {
pDialog.dismiss();
pDialog = null;
}
}
private void populateSpinner() {
List<String> lables = new ArrayList<String>();
for (int i = 0; i < spinnerList.size(); i++) {
lables.add(spinnerList.get(i).getPackingnm());
}
// Creating adapter for spinner
ArrayAdapter<String> spinnerAdapter = new ArrayAdapter<String>(getActivity().getBaseContext(), android.R.layout.simple_spinner_item, lables);
// Drop down layout style - list view with radio button spinnerAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
// attaching data adapter to spinner
spinnerPacking.setAdapter(spinnerAdapter);
}
}
请帮助。感谢
fragment_vegetable.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity" >
<ListView
android:id="@+id/list"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:divider="@color/list_divider"
android:dividerHeight="1dp"
android:listSelector="@drawable/list_row_selector" />
</RelativeLayout>
适配器GetView方法：
@Override
public View getView(int position, View convertView, ViewGroup parent) {
if (inflater == null)
inflater = (LayoutInflater) activity.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
if (convertView == null) convertView = inflater.inflate(R.layout.list_row, null);
TextView title = (TextView) convertView.findViewById(R.id.title);
if (imageLoader == null)
imageLoader = AppController.getInstance().getImageLoader();
NetworkImageView thumbNail = (NetworkImageView) convertView.findViewById(R.id.thumbnail);
TextView ourPrice = (TextView) convertView.findViewById(R.id.ourPrice);
TextView packing = (TextView) convertView.findViewById(R.id.packing);
TextView marketPrice = (TextView) convertView.findViewById(R.id.marketPrice);
Spinner packingSpinner = (Spinner) convertView.findViewById(R.id.packingList);
packingSpinner.setOnItemSelectedListener(this);
// getting products data for the row
Products p = productsItems.get(position);
// thumbnail image
thumbNail.setImageUrl(p.getThumbnailUrl(), imageLoader);
// title
title.setText(p.getTitle());
// ourPrice
ourPrice.setText("Our Price: " + String.valueOf(p.getOurPrice()));
// packing
List<String> lables = new ArrayList<String>();
for (int i = 0; i < p.getPacking().size(); i++) {
lables.add(p.getPacking().get(i));
}
// Creating adapter for spinner
ArrayAdapter<String> spinnerAdapter = new ArrayAdapter<String>(context,android.R.layout.simple_spinner_item, lables);
// Drop down layout style - list view with radio button
spinnerAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
// attaching data adapter to spinner
packingSpinner.setAdapter(spinnerAdapter);
String packingStr = "";
for (String str : p.getPacking()) {
packingStr += str + ", ";
}
packingStr = packingStr.length() > 0 ? packingStr.substring(0,
packingStr.length() - 2) : packingStr;
packing.setText(packingStr);
// marketPrice
marketPrice.setText("Market Price: " + String.valueOf(p.getMarketPrice()));
marketPrice.setPaintFlags(marketPrice.getPaintFlags() | Paint.STRIKE_THRU_TEXT_FLAG);
return convertView;
}
当你得到错误？不要在Oncreate中添加太多的代码。 –
错误发生在json执行完成后，它初始化了微调器的onitemselected侦听器。 – shivendra1046