Ich versuche, ein zuvor Activity-basierte Tutorial in ein Fragment zu konvertieren, aber ich fahre fort, in den NullPointerException-Fehler auf meinem Adapter zu laufen.Android Volley Null Pointer Ausnahme
Das Tutorial basiert auf this und ich habe den Konstruktor für den Adapter abgespeckt, weil es eine Aktivität aufgerufen hat.
Es gibt eine mögliche Lösung here aber niemand weiß, wie man mit der gleichen möglichen Frage fortfährt.
Ich möchte alles in ein funktionierendes Fragment umwandeln. Bitte lassen Sie mich wissen, wenn Sie weitere Informationen von mir benötigen.
Haupt konvertierte Klasse:
public class mainViewController2 extends Fragment {
private static final String TAG = mainViewController2.class.getSimpleName();
private ListView listView;
private FeedListAdapter listAdapter;
private List<FeedItem> feedItems;
private String URL_FEED = "http://api.androidhive.info/feed/feed.json";
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View v = inflater.inflate(R.layout.mainviewcontroller2_fragment, container, false);
listView = (ListView) v.findViewById(R.id.list);
feedItems = new ArrayList<FeedItem>();
//where the error shows up?
listAdapter = new FeedListAdapter(feedItems);
listView.setAdapter(listAdapter);
// We first check for cached request
Cache cache = AppController.getInstance().getRequestQueue().getCache();
Entry entry = cache.get(URL_FEED);
if (entry != null) {
// fetch the data from cache
try {
String data = new String(entry.data, "UTF-8");
try {
parseJsonFeed(new JSONObject(data));
} catch (JSONException e) {
e.printStackTrace();
}
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
}
} else {
// making fresh volley request and getting json
JsonObjectRequest jsonReq = new JsonObjectRequest(Method.GET,
URL_FEED, null, new Response.Listener<JSONObject>() {
@Override
public void onResponse(JSONObject response) {
VolleyLog.d(TAG, "Response: " + response.toString());
if (response != null) {
parseJsonFeed(response);
}
}
}, new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
VolleyLog.d(TAG, "Error: " + error.getMessage());
}
});
// Adding request to volley request queue
AppController.getInstance().addToRequestQueue(jsonReq);
}
return v;
}
/**
* Parsing json reponse and passing the data to feed view list adapter
* */
private void parseJsonFeed(JSONObject response) {
try {
JSONArray feedArray = response.getJSONArray("feed");
for (int i = 0; i < feedArray.length(); i++) {
JSONObject feedObj = (JSONObject) feedArray.get(i);
FeedItem item = new FeedItem();
item.setId(feedObj.getInt("id"));
item.setName(feedObj.getString("name"));
// Image might be null sometimes
String image = feedObj.isNull("image") ? null : feedObj
.getString("image");
item.setImge(image);
item.setStatus(feedObj.getString("status"));
item.setProfilePic(feedObj.getString("profilePic"));
item.setTimeStamp(feedObj.getString("timeStamp"));
// url might be null sometimes
String feedUrl = feedObj.isNull("url") ? null : feedObj
.getString("url");
item.setUrl(feedUrl);
feedItems.add(item);
}
// notify data changes to list adapater
listAdapter.notifyDataSetChanged();
} catch (JSONException e) {
e.printStackTrace();
}
}
}
FeedListAdapter:
public class FeedListAdapter extends BaseAdapter {
private Activity activity;
private LayoutInflater inflater;
private List<FeedItem> feedItems;
Context context;
ImageLoader imageLoader;
public FeedListAdapter(Context ctx,List<FeedItem> feedItems) {
this.context= ctx;
this.feedItems = feedItems;
imageLoader = AppController.getInstance().getImageLoader();
inflater = LayoutInflater.from(context);
}
@Override
public int getCount() {
return feedItems.size();
}
@Override
public Object getItem(int location) {
return feedItems.get(location);
}
@Override
public long getItemId(int position) {
return position;
}
@SuppressLint("InflateParams")
@Override
public View getView(int position, View convertView, ViewGroup parent) {
if (inflater == null)
inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
if (convertView == null)
convertView = inflater.inflate(R.layout.feed_item, null);
if (imageLoader == null)
imageLoader = AppController.getInstance().getImageLoader();
TextView name = (TextView) convertView.findViewById(R.id.name);
TextView timestamp = (TextView) convertView
.findViewById(R.id.timestamp);
TextView statusMsg = (TextView) convertView
.findViewById(R.id.txtStatusMsg);
TextView url = (TextView) convertView.findViewById(R.id.txtUrl);
NetworkImageView profilePic = (NetworkImageView) convertView
.findViewById(R.id.profilePic);
FeedImageView feedImageView = (FeedImageView) convertView
.findViewById(R.id.feedImage1);
FeedItem item = feedItems.get(position);
name.setText(item.getName());
// Converting timestamp into x ago format
CharSequence timeAgo = DateUtils.getRelativeTimeSpanString(
Long.parseLong(item.getTimeStamp()),
System.currentTimeMillis(), DateUtils.SECOND_IN_MILLIS);
timestamp.setText(timeAgo);
// Chcek for empty status message
if (!TextUtils.isEmpty(item.getStatus())) {
statusMsg.setText(item.getStatus());
statusMsg.setVisibility(View.VISIBLE);
} else {
// status is empty, remove from view
statusMsg.setVisibility(View.GONE);
}
// Checking for null feed url
if (item.getUrl() != null) {
url.setText(Html.fromHtml("<a href=\"" + item.getUrl() + "\">"
+ item.getUrl() + "</a> "));
// Making url clickable
url.setMovementMethod(LinkMovementMethod.getInstance());
url.setVisibility(View.VISIBLE);
} else {
// url is null, remove from the view
url.setVisibility(View.GONE);
}
// user profile pic
profilePic.setImageUrl(item.getProfilePic(), imageLoader);
// Feed image
if (item.getImge() != null) {
feedImageView.setImageUrl(item.getImge(), imageLoader);
feedImageView.setVisibility(View.VISIBLE);
feedImageView
.setResponseObserver(new FeedImageView.ResponseObserver() {
@Override
public void onError() {
}
@Override
public void onSuccess() {
}
});
} else {
feedImageView.setVisibility(View.GONE);
}
return convertView;
}
}
LogCat Fehler:
09-06 02:51:55.823: E/AndroidRuntime(8279): FATAL EXCEPTION: main
09-06 02:51:55.823: E/AndroidRuntime(8279): Process: com.rynovation.kline, PID: 8279
09-06 02:51:55.823: E/AndroidRuntime(8279): java.lang.NullPointerException
09-06 02:51:55.823: E/AndroidRuntime(8279): at androidFeedClasses.FeedListAdapter.<init>(FeedListAdapter.java:35)
09-06 02:51:55.823: E/AndroidRuntime(8279): at com.rynovation.kline.mainViewController2.onCreateView(mainViewController2.java:51)
09-06 02:51:55.823: E/AndroidRuntime(8279): at android.app.Fragment.performCreateView(Fragment.java:1700)
09-06 02:51:55.823: E/AndroidRuntime(8279): at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:890)
09-06 02:51:55.823: E/AndroidRuntime(8279): at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:1062)
09-06 02:51:55.823: E/AndroidRuntime(8279): at android.app.BackStackRecord.run(BackStackRecord.java:684)
09-06 02:51:55.823: E/AndroidRuntime(8279): at android.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1453)
09-06 02:51:55.823: E/AndroidRuntime(8279): at android.app.FragmentManagerImpl$1.run(FragmentManager.java:443)
09-06 02:51:55.823: E/AndroidRuntime(8279): at android.os.Handler.handleCallback(Handler.java:733)
09-06 02:51:55.823: E/AndroidRuntime(8279): at android.os.Handler.dispatchMessage(Handler.java:95)
09-06 02:51:55.823: E/AndroidRuntime(8279): at android.os.Looper.loop(Looper.java:146)
09-06 02:51:55.823: E/AndroidRuntime(8279): at android.app.ActivityThread.main(ActivityThread.java:5487)
09-06 02:51:55.823: E/AndroidRuntime(8279): at java.lang.reflect.Method.invokeNative(Native Method)
09-06 02:51:55.823: E/AndroidRuntime(8279): at java.lang.reflect.Method.invoke(Method.java:515)
09-06 02:51:55.823: E/AndroidRuntime(8279): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1283)
09-06 02:51:55.823: E/AndroidRuntime(8279): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1099)
09-06 02:51:55.823: E/AndroidRuntime(8279): at dalvik.system.NativeStart.main(Native Method)
Ihre Adapter ist überall. Lesen Sie über das ViewHolder-Muster und versuchen Sie, etwas Ähnliches zu erstellen. Hier ist die Google-Version, aber versuchen Sie auch, nach Beispielen zu suchen: http://developer.android.com/training/improving-layouts/smooth-scrolling.html –