我有问题在arraylist中添加新数据。当调用LoadData对象Iteamcher有新数据但我不知道追加它。所以当我设置数据时，listview会发生NullPointerException。
我需要帮助。请编辑我的代码。
非常感谢！
public class InfoTeacherFragment extends Fragment {
private String URL = "http://scv.udn.vn/dhdn/trdhsp/page/";
ProgressDialog pDialog;
Context mContext;
private ArrayList<ItemTeacher> data;
// ItemTeacher itemTeacher;
// ArrayList<String> Name;
// ArrayList<String> School;
// ArrayList<String> Link;
// ArrayList<String> Icon;
ListView lvItem;
DisplayImageOptions options;
ImageLoader imageloader;
View mFooterView;
InfoTeacher adapter;
ProgressBar loading;
int CurrentPage = 1;
int visibleThreshold = 3;
int startPage = 1;
boolean loadingMore = false;
public InfoTeacherFragment() {
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
options = new DisplayImageOptions.Builder()
.showImageOnLoading(R.drawable.ic_mission)
.showImageForEmptyUri(R.drawable.ic_empty)
.showImageOnFail(R.drawable.ic_error).cacheInMemory(true)
.cacheOnDisk(true).considerExifParams(true)
.bitmapConfig(Bitmap.Config.RGB_565).build();
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.teacherinfo_layout,
container, false);
mContext = container.getContext();
lvItem = (ListView) rootView.findViewById(R.id.lvTeacher);
data = new ArrayList<ItemTeacher>();
adapter = new InfoTeacher(mContext, data);
lvItem.setOnScrollListener(new EndlessScrollListener() {
@Override
public void onLoadMore(int page, int totalItemsCount) {
CurrentPage++;
customLoadMoreDataFromApi(CurrentPage);
}
});
imageloader = ImageLoader.getInstance();
imageloader.init(ImageLoaderConfiguration.createDefault(mContext));
if (Utils.isOnline(mContext) == true
&& Utils.KEY_CHECK_SUCCESS.equals("SUCCESS")) {
loadDataFromServer(URL + startPage);
} else if (Utils.isOnline(mContext) == true
&& Utils.KEY_CHECK_SUCCESS.equals("FAIL")) {
Utils.MyToast(Utils.KEYWORK_ERROR[0], R.drawable.warning_icon,
mContext, false);
}
isInitList = true;
lvItem.setAdapter(adapter);
lvItem.setOnItemClickListener(new OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> adapter1, View view,
int position, long id) {
Intent intent = new Intent(mContext, NewsItemView.class);
if (!adapter.getItem(position).getLink().get(position)
.equalsIgnoreCase("")) {
Bundle bundle = new Bundle();
bundle.putSerializable(NewsItemView.ITEM_TEACHER,
adapter.getItemId(position));
bundle.putInt(NewsItemView.POSITION, position);
intent.putExtras(bundle);
startActivity(intent);
}
}
});
return rootView;
}
private void loadDataFromServer(String URL) {
LoadData loadData = new LoadData() {
@Override
protected void onPostExecute(ArrayList<ItemTeacher> result) {
super.onPostExecute(result);
updateListView(result);
}
};
loadData.execute(URL);
}
boolean isInitList = false;
protected void updateListView(ArrayList<ItemTeacher> result) {
if (!isInitList) {
data.addAll(result);
}
isInitList = false;
// else{
// isInitList = false;
// adapter.clear();
// adapter.addAll(result);
// }
adapter.clear();
adapter.addAll(result);
adapter.notifyDataSetChanged();
}
@Override
public void onDestroy() {
super.onDestroy();
AnimateFirstDisplayListener.displayedImages.clear();
}
class LoadData extends AsyncTask<String, Void, ArrayList<ItemTeacher>> {
@Override
protected void onPreExecute() {
pDialog = ProgressDialog.show(mContext, "", Utils.KEYWORK_ERROR[2]);
data = new ArrayList<ItemTeacher>();
super.onPreExecute();
}
@Override
protected ArrayList<ItemTeacher> doInBackground(String... params) {
data = Utils.getInformationTeacher(params[0]);
return data;
}
@Override
protected void onPostExecute(ArrayList<ItemTeacher> result) {
if (result != null) {
pDialog.dismiss();
} else if (result == null) {
pDialog.dismiss();
Utils.MyToast(Utils.KEYWORK_ERROR[0], R.drawable.warning_icon,
mContext, false);
}
super.onPostExecute(result);
}
}
class InfoTeacher extends ArrayAdapter<ItemTeacher> {
private LayoutInflater inflater;
ImageLoadingListener animateFirstListener;
List<ItemTeacher> item = new ArrayList<ItemTeacher>();
public InfoTeacher(Context context, List<ItemTeacher> objects) {
super(context, -1, objects);
this.item = objects;
inflater = (LayoutInflater) context
.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
animateFirstListener = new AnimateFirstDisplayListener();
}
@Override
public View getView(int position, View convertView, ViewGroup arg2) {
ItemTeacher itemTeacher = getItem(position);
ViewHolder holder;
if (convertView == null) {
holder = new ViewHolder();
convertView = inflater.inflate(R.layout.teacher_layout, arg2,
false);
holder.Name = (TextView) convertView
.findViewById(R.id.tv_NameTeacher);
holder.School = (TextView) convertView
.findViewById(R.id.tv_School);
holder.ic_naviga = (ImageView) convertView
.findViewById(R.id.ivNaviga);
holder.icon = (ImageView) convertView
.findViewById(R.id.iv_IconTeacher);
convertView.setTag(holder);
} else
holder = (ViewHolder) convertView.getTag();
holder.Name.setText(itemTeacher.getName().get(position));
holder.School.setText(itemTeacher.getSchool().get(position));
return convertView;
}
@Override
public int getCount() {
return item.size();
}
}
static class ViewHolder {
ImageView icon;
TextView Name;
TextView School;
ImageView ic_naviga;
}
private static class AnimateFirstDisplayListener extends
SimpleImageLoadingListener {
static final List<String> displayedImages = Collections
.synchronizedList(new LinkedList<String>());
@Override
public void onLoadingComplete(String imageUri, View view,
Bitmap loadedImage) {
if (loadedImage != null) {
ImageView imageView = (ImageView) view;
boolean firstDisplay = !displayedImages.contains(imageUri);
if (firstDisplay) {
FadeInBitmapDisplayer.animate(imageView, 500);
displayedImages.add(imageUri);
}
}
}
}
public void customLoadMoreDataFromApi(int page) {
loadDataFromServer(URL + page);
}
}
And Object ItemTeacher
public class ItemTeacher {
private ArrayList<String> name = new ArrayList<String>();
private ArrayList<String> icon = new ArrayList<String>();
private ArrayList<String> link = new ArrayList<String>();
private ArrayList<String> school = new ArrayList<String>();
public ItemTeacher(){
}
public ArrayList<String> getIcon() {
return icon;
}
public ArrayList<String> getLink() {
return link;
}
public ArrayList<String> getName() {
return name;
}
public ArrayList<String> getSchool() {
return school;
}
public void setIcon(ArrayList<String> icon) {
this.icon = icon;
}
public void setLink(ArrayList<String> link) {
this.link = link;
}
public void setName(ArrayList<String> name) {
this.name = name;
}
public void setSchool(ArrayList<String> school) {
this.school = school;
}
}
并给我错误＆＃34; NullPointerException＆＃34;
01-02 06:26:23.105: E/InputEventReceiver(1281): Exception dispatching input event.
01-02 06:26:23.121: E/AndroidRuntime(1281): FATAL EXCEPTION: main
01-02 06:26:23.121: E/AndroidRuntime(1281): java.lang.IndexOutOfBoundsException: Invalid index 30, size is 30
01-02 06:26:23.121: E/AndroidRuntime(1281): at java.util.ArrayList.throwIndexOutOfBoundsException(ArrayList.java:251)
01-02 06:26:23.121: E/AndroidRuntime(1281): at java.util.ArrayList.get(ArrayList.java:304)
01-02 06:26:23.121: E/AndroidRuntime(1281): at android.readnews.main.InfoTeacherFragment$InfoTeacher.getView(InfoTeacherFragment.java:227)
01-02 06:26:23.121: E/AndroidRuntime(1281): at android.widget.AbsListView.obtainView(AbsListView.java:2143)
01-02 06:26:23.121: E/AndroidRuntime(1281): at android.widget.ListView.makeAndAddView(ListView.java:1831)
01-02 06:26:23.121: E/AndroidRuntime(1281): at android.widget.ListView.fillDown(ListView.java:674)
01-02 06:26:23.121: E/AndroidRuntime(1281): at android.widget.ListView.fillGap(ListView.java:638)
01-02 06:26:23.121: E/AndroidRuntime(1281): at android.widget.AbsListView.trackMotionScroll(AbsListView.java:4930)
01-02 06:26:23.121: E/AndroidRuntime(1281): at android.widget.AbsListView.scrollIfNeeded(AbsListView.java:3087)
01-02 06:26:23.121: E/AndroidRuntime(1281): at android.widget.AbsListView.onTouchEvent(AbsListView.java:3361)
01-02 06:26:23.121: E/AndroidRuntime(1281): at android.view.View.dispatchTouchEvent(View.java:7246)
01-02 06:26:23.121: E/AndroidRuntime(1281): at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2168)
01-02 06:26:23.121: E/AndroidRuntime(1281): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1903)
01-02 06:26:23.121: E/AndroidRuntime(1281): at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2174)
01-02 06:26:23.121: E/AndroidRuntime(1281): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1917)
01-02 06:26:23.121: E/AndroidRuntime(1281): at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2174)
01-02 06:26:23.121: E/AndroidRuntime(1281): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1917)
01-02 06:26:23.121: E/AndroidRuntime(1281): at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2174)
01-02 06:26:23.121: E/AndroidRuntime(1281): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1917)
01-02 06:26:23.121: E/AndroidRuntime(1281): at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2174)
01-02 06:26:23.121: E/AndroidRuntime(1281): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1917)
01-02 06:26:23.121: E/AndroidRuntime(1281): at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2174)
01-02 06:26:23.121: E/AndroidRuntime(1281): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1917)
01-02 06:26:23.121: E/AndroidRuntime(1281): at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2174)
01-02 06:26:23.121: E/AndroidRuntime(1281): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1917)
01-02 06:26:23.121: E/AndroidRuntime(1281): at com.android.internal.policy.impl.PhoneWindow$DecorView.superDispatchTouchEvent(PhoneWindow.java:1953)
01-02 06:26:23.121: E/AndroidRuntime(1281): at com.android.internal.policy.impl.PhoneWindow.superDispatchTouchEvent(PhoneWindow.java:1405)
01-02 06:26:23.121: E/AndroidRuntime(1281): at android.app.Activity.dispatchTouchEvent(Activity.java:2410)
01-02 06:26:23.121: E/AndroidRuntime(1281): at com.android.internal.policy.impl.PhoneWindow$DecorView.dispatchTouchEvent(PhoneWindow.java:1901)
01-02 06:26:23.121: E/AndroidRuntime(1281): at android.view.View.dispatchPointerEvent(View.java:7426)
01-02 06:26:23.121: E/AndroidRuntime(1281): at android.view.ViewRootImpl.deliverPointerEvent(ViewRootImpl.java:3220)
01-02 06:26:23.121: E/AndroidRuntime(1281): at android.view.ViewRootImpl.deliverInputEvent(ViewRootImpl.java:3165)
01-02 06:26:23.121: E/AndroidRuntime(1281): at android.view.ViewRootImpl.doProcessInputEvents(ViewRootImpl.java:4292)
01-02 06:26:23.121: E/AndroidRuntime(1281): at android.view.ViewRootImpl.enqueueInputEvent(ViewRootImpl.java:4271)
01-02 06:26:23.121: E/AndroidRuntime(1281): at android.view.ViewRootImpl$WindowInputEventReceiver.onInputEvent(ViewRootImpl.java:4363)
01-02 06:26:23.121: E/AndroidRuntime(1281): at android.view.InputEventReceiver.dispatchInputEvent(InputEventReceiver.java:179)
01-02 06:26:23.121: E/AndroidRuntime(1281): at android.view.InputEventReceiver.nativeConsumeBatchedInputEvents(Native Method)
01-02 06:26:23.121: E/AndroidRuntime(1281): at android.view.InputEventReceiver.consumeBatchedInputEvents(InputEventReceiver.java:171)
01-02 06:26:23.121: E/AndroidRuntime(1281): at android.view.ViewRootImpl.doConsumeBatchedInput(ViewRootImpl.java:4342)
01-02 06:26:23.121: E/AndroidRuntime(1281): at android.view.ViewRootImpl$ConsumeBatchedInputRunnable.run(ViewRootImpl.java:4382)
01-02 06:26:23.121: E/AndroidRuntime(1281): at android.view.Choreographer$CallbackRecord.run(Choreographer.java:749)
01-02 06:26:23.121: E/AndroidRuntime(1281): at android.view.Choreographer.doCallbacks(Choreographer.java:562)
01-02 06:26:23.121: E/AndroidRuntime(1281): at android.view.Choreographer.doFrame(Choreographer.java:530)
01-02 06:26:23.121: E/AndroidRuntime(1281): at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:735)
01-02 06:26:23.121: E/AndroidRuntime(1281): at android.os.Handler.handleCallback(Handler.java:725)
01-02 06:26:23.121: E/AndroidRuntime(1281): at android.os.Handler.dispatchMessage(Handler.java:92)
01-02 06:26:23.121: E/AndroidRuntime(1281): at android.os.Looper.loop(Looper.java:137)
01-02 06:26:23.121: E/AndroidRuntime(1281): at android.app.ActivityThread.main(ActivityThread.java:5041)
01-02 06:26:23.121: E/AndroidRuntime(1281): at java.lang.reflect.Method.invokeNative(Native Method)
01-02 06:26:23.121: E/AndroidRuntime(1281): at java.lang.reflect.Method.invoke(Method.java:511)
01-02 06:26:23.121: E/AndroidRuntime(1281): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
01-02 06:26:23.121: E/AndroidRuntime(1281): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
01-02 06:26:23.121: E/AndroidRuntime(1281): at dalvik.system.NativeStart.main(Native Method)
答案 0 :(得分：0)
袖手旁观，并且不确定我理解这个问题，但是，我不确定for循环应该在那里：
protected void updateListView(ArrayList<ItemTeacher> result) {
for (int i = 0, n = result.size(); i < n; i++) {
adapter.addAll(result);
}
adapter.notifyDataSetChanged();
}
我在这里更新了一个ArrayList。试试.clear（）：
myAdapter.clear();
myAdapter.addAll(myDisplayList);
myAdapter.notifyDataSetChanged();