我有一个对象列表，它们会进入列表视图。当单击listview中的项目时，我想要一个新的片段打开来自新片段中我的对象的数据。当我点击listview中的项目时，我收到此错误：
06-26 11:05:47.564 14384-14384/com.beerportfolio.beerportfoliopro E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: com.beerportfolio.beerportfoliopro, PID: 14384
java.lang.NullPointerException
at com.beerportfolio.beerportfoliopro.GetLocationsJSON$1.onItemClick(GetLocationsJSON.java:132)
at android.widget.AdapterView.performItemClick(AdapterView.java)
at android.widget.AbsListView.performItemClick(AbsListView.java)
at android.widget.AbsListView$PerformClick.run(AbsListView.java)
at android.widget.AbsListView$3.run(AbsListView.java)
at android.os.Handler.handleCallback(Handler.java)
at android.os.Handler.dispatchMessage(Handler.java)
at android.os.Looper.loop(Looper.java)
at android.app.ActivityThread.main(ActivityThread.java)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java)
at dalvik.system.NativeStart.main(Native Method)
发生崩溃的代码：
public class GetLocationsJSON extends AsyncTask<String, Void, String> {
Context c;
private ProgressDialog Dialog;
public GetLocationsJSON(Context context)
{
c = context;
Dialog = new ProgressDialog(c);
}
//****************code for on click
OnArticleSelectedListener listenerBeer;
public interface OnArticleSelectedListener{
public void onArticleSelected(LocationData d);
}
public void setOnArticleSelectedListener(OnArticleSelectedListener listener){
this.listenerBeer = listener;
}
//******************end code for onClick
@Override
protected String doInBackground(String... arg0) {
// TODO Auto-generated method stub
return readJSONFeed(arg0[0]);
}
protected void onPreExecute() {
Dialog.setMessage("Searching For Brewery Locations");
Dialog.setTitle("Loading");
Dialog.show();
}
protected void onPostExecute(String result){
//decode json here
try{
JSONObject json = new JSONObject(result);
//acces listview
ListView lv = (ListView) ((Activity) c).findViewById(R.id.locationlist);
//make array list for beer
final List<LocationData> beerList = new ArrayList<LocationData>();
String phone;
String hours;
//get json items
for(int i = 0; i < json.getJSONObject("data").getJSONArray("locations").length(); i++) {
String name = json.getJSONObject("data").getJSONArray("locations").getJSONObject(i).getString("name");
Log.d("location" , name);
try {
phone = json.getJSONObject("data").getJSONArray("locations").getJSONObject(i).getString("phone");
}
catch(JSONException e){
phone = "N/A";
}
String lat = json.getJSONObject("data").getJSONArray("locations").getJSONObject(i).getString("latitude");
String longitude = json.getJSONObject("data").getJSONArray("locations").getJSONObject(i).getString("longitude");
String open = json.getJSONObject("data").getJSONArray("locations").getJSONObject(i).getString("openToPublic");
try {
hours = json.getJSONObject("data").getJSONArray("locations").getJSONObject(i).getString("hoursOfOperation");
}
catch (JSONException e){
hours = "N/A";
}
String type = json.getJSONObject("data").getJSONArray("locations").getJSONObject(i).getString("locationTypeDisplay");
//todo: create location object
LocationData thisBeer = new LocationData(name, phone, lat, longitude, open, hours, type);
//add beer to list
beerList.add(thisBeer);
}
//update listview
LocationAdapter adapter1 = new LocationAdapter(c ,R.layout.listview_item_row, beerList);
lv.setAdapter(adapter1);
//set up clicks
lv.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> arg0, View arg1,
int arg2, long arg3) {
LocationData beerInfo = beerList.get(arg2);
//************************Launch listener interface
listenerBeer.onArticleSelected(beerInfo);
}
});
}
catch(Exception e){
}
Dialog.dismiss();
}
上述代码中发生崩溃的第132行是：
listenerBeer.onArticleSelected(beerInfo);
听众的其余部分在这里：
public class BreweryLocations extends Fragment implements GetLocationsJSON.OnArticleSelectedListener {
String beerId = "";
Dialog dialog = null;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
//set layout here
View v = inflater.inflate(R.layout.brewerylocation_page, container, false);
setHasOptionsMenu(true);
//get user information
SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(getActivity());
String userName = prefs.getString("userName", null);
String userID = prefs.getString("userID", null);
//Todo: code for retrieving brewery location
String breweryId = prefs.getString("breweryID", null);
String url2 = "myURL";
//call async task now!
new GetLocationsJSON(getActivity()).execute(url2);
Log.d("location" , url2);
// Inflate the layout for this fragment
return v;
}
@Override
public void onArticleSelected(LocationData d){
//code to execute on click
Fragment Fragment_one;
FragmentManager man= getFragmentManager();
FragmentTransaction tran = man.beginTransaction();
//adds beer data to shared prefs for beer tabs
SharedPreferences preferences = PreferenceManager.getDefaultSharedPreferences(getActivity());
SharedPreferences.Editor editor = preferences.edit();
editor.putString("name",d.name);
editor.putString("hours",d.hours);
editor.putString("lat",d.lat);
editor.putString("lng",d.lng);
editor.putString("phone",d.phone);
editor.commit();
Fragment_one = new BeerTabs();
tran.replace(R.id.main, Fragment_one);//tran.
tran.addToBackStack(null);
tran.commit();
}
}
答案 0 :(得分：1)
看起来你的listenerBeer为null。
尝试更改
//call async task now!
new GetLocationsJSON(getActivity()).execute(url2);
到
GetLocationsJSON locationJson = new GetLocationJSON(getActivity());
locationJson.setOnArticleSelectedListener(this);
locationJson.execute(url2);