我是android新手。我正在尝试使用自定义适配器初始化片段中的listview，但我在使用自定义适配器构造函数时遇到问题。
这是我的自定义适配器代码。
public class CustomListAdapter extends BaseAdapter {
private Activity activity;
private LayoutInflater inflater;
private List<Movie> movieItems;
ImageLoader imageLoader = AppController.getInstance().getImageLoader();
public CustomListAdapter(Activity activity, List<Movie> movieItems) {
this.activity = activity;
this.movieItems = movieItems;
}
@Override
public int getCount() {
return movieItems.size();
}
@Override
public Object getItem(int location) {
return movieItems.get(location);
}
@Override
public long getItemId(int position) {
return position;
}
@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);
if (imageLoader == null)
imageLoader = AppController.getInstance().getImageLoader();
NetworkImageView thumbNail = (NetworkImageView) convertView
.findViewById(R.id.thumbnail);
TextView title = (TextView) convertView.findViewById(R.id.title);
TextView rating = (TextView) convertView.findViewById(R.id.rating);
TextView genre = (TextView) convertView.findViewById(R.id.genre);
TextView year = (TextView) convertView.findViewById(R.id.releaseYear);
// getting movie data for the row
Movie m = movieItems.get(position);
// thumbnail image
thumbNail.setImageUrl(m.getThumbnailUrl(), imageLoader);
// title
title.setText(m.getTitle());
// rating
rating.setText("Rating: " + String.valueOf(m.getRating()));
// genre
String genreStr = "";
for (String str : m.getGenre())
{
genreStr += str + ", ";
}
genreStr = genreStr.length() > 0 ? genreStr.substring(0, genreStr.length() - 2) : genreStr;
genre.setText(genreStr);
// release year
year.setText(String.valueOf(m.getYear()));
return convertView;
}
}
这是我的片段激活码。
private ProgressDialog pDialog;
private List<Movie> movieList = new ArrayList<Movie>();
private ListView listView;
private CustomListAdapter adapter;
private Custom_Adapter_Fragment adapter2;
@Override
public void onActivityCreated(@Nullable Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
// ArrayAdapter<CharSequence> adapter = ArrayAdapter.createFromResource(getActivity(), R.array.Planets, android.R.layout.simple_list_item_1);
// adapter = new CustomListAdapter(this.getActivity(), movieList);
//
// adapter = new CustomListAdapter(this.getActivity(), movieList);
adapter2 = new Custom_Adapter_Fragment(movieList,getContext());
}
@Nullable
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.news,null);
listView = (ListView)view.findViewById(android.R.id.list);
listView.setAdapter(adapter);
pDialog = new ProgressDialog(getContext());
// Showing progress dialog before making http request
pDialog.setMessage("Loading...");
pDialog.show();
JsonArrayRequest movieReq = 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);
Movie movie = new Movie();
movie.setTitle(obj.getString("title"));
movie.setThumbnailUrl(obj.getString("image"));
movie.setRating(((Number) obj.get("rating"))
.doubleValue());
movie.setYear(obj.getInt("releaseYear"));
// Genre is json array
JSONArray genreArry = obj.getJSONArray("genre");
ArrayList<String> genre = new ArrayList<String>();
for (int j = 0; j < genreArry.length(); j++) {
genre.add((String) genreArry.get(j));
}
movie.setGenre(genre);
// adding movie to movies array
movieList.add(movie);
} 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(movieReq);
return view;
}
private void hidePDialog() {
if (pDialog != null) {
pDialog.dismiss();
pDialog = null;
}
}
}
这是我的logcat
03-13 19:56:16.036 17211-17211/com.example.krunal.anamika E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.krunal.anamika, PID: 17211
java.lang.NullPointerException
at com.example.krunal.anamika.fragments.News.onCreateView(News.java:125)
at android.support.v4.app.Fragment.performCreateView(Fragment.java:1974)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1067)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1252)
at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:738)
at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1617)
at android.support.v4.app.FragmentManagerImpl.executePendingTransactions(FragmentManager.java:570)
at android.support.v4.app.FragmentPagerAdapter.finishUpdate(FragmentPagerAdapter.java:141)
at android.support.v4.view.ViewPager.populate(ViewPager.java:1177)
at android.support.v4.view.ViewPager.populate(ViewPager.java:1025)
at android.support.v4.view.ViewPager.onMeasure(ViewPager.java:1545)
at android.view.View.measure(View.java:16660)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5150)
at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1404)
at android.widget.LinearLayout.measureVertical(LinearLayout.java:695)
at android.widget.LinearLayout.onMeasure(LinearLayout.java:588)
at android.view.View.measure(View.java:16660)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5150)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
at android.view.View.measure(View.java:16660)
at android.support.v4.widget.DrawerLayout.onMeasure(DrawerLayout.java:1075)
at android.view.View.measure(View.java:16660)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5150)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
at android.support.v7.widget.ContentFrameLayout.onMeasure(ContentFrameLayout.java:135)
at android.view.View.measure(View.java:16660)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5150)
at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1404)
at android.widget.LinearLayout.measureVertical(LinearLayout.java:695)
at android.widget.LinearLayout.onMeasure(LinearLayout.java:588)
at android.view.View.measure(View.java:16660)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5150)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
at android.view.View.measure(View.java:16660)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5150)
at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1404)
at android.widget.LinearLayout.measureVertical(LinearLayout.java:695)
at android.widget.LinearLayout.onMeasure(LinearLayout.java:588)
at android.view.View.measure(View.java:16660)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5150)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2421)
at android.view.View.measure(View.java:16660)
at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:2058)
at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1189)
at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1374)
at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1076)
at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:5905)
at android.view.Choreographer$CallbackRecord.run(Choreographer.java:807)
at android.view.Choreographer.doCallbacks(Choreographer.java:601)
at android.view.Choreographer.doFrame(Choreographer.java:562)
at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:791)
at android.os.Handler.handleCallback(Handler.java:733)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:157)
at android.app.ActivityThread.main(ActivityThread.java:5633)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.i
我知道问题出在自定义适配器构造函数中。
先谢谢。