我收到此错误 - 尝试在空对象引用上调用虚方法'int java.util.ArrayList.size（）'
这就是我所做的！
PeopleListFragment
**PeopleListFragment**
public class PeopleListFragment extends Fragment{
public static final String DISPLAY_URL = ServiceAPI.URL_CONTACTS;
private static final String TAG = "PeopleListActivity";
public static final boolean DEBUG = Constant.DEBUG;
private ProgressDialog progressDialog;
public PeopleAdapter adapter;
private GetAllPeopleTask mGetAllPeople = null;
private Intent intent;
public static ListView mContactlistView;
public PeopleListFragment() {
// Required empty public constructor
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
return inflater.inflate(R.layout.fragment_people_list, container, false);
}
@Override
public void onViewCreated(View view, Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
mContactlistView = (ListView) view.findViewById(R.id.people_list);
}
@Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
List<People> contactList = new ArrayList<People>();
adapter = new PeopleAdapter(getActivity().getApplicationContext(),
R.layout.people_list_item, contactList);
mContactlistView.setAdapter(adapter);
mContactlistView.setTextFilterEnabled(true);
mContactlistView.setFastScrollEnabled(true);
mContactlistView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
String empId = String.valueOf(adapter.getItem(position).getEmployeeId());
String name = String.valueOf(adapter.getItem(position).getFirstName());
intent = new Intent(getActivity(),
PeopleDetailsActivity.class);
intent.putExtra("EmployeeId", empId);
intent.putExtra("name", name);
startActivity(intent);
}
});
startAsyncTask();
TextView textView = new TextView(getContext());
textView.setText("Empty");
mContactlistView.setEmptyView(textView);
}
public void startAsyncTask() {
mGetAllPeople = new GetAllPeopleTask();
mGetAllPeople.execute(DISPLAY_URL, "12345678");
}
public class GetAllPeopleTask extends AsyncTask<String, Void, List<People>> {
@Override
protected void onPreExecute() {
super.onPreExecute();
progressDialog = new ProgressDialog(getActivity());
progressDialog.setMessage("Loading");
progressDialog.show();
}
@Override
protected ArrayList<People> doInBackground(String... params) {
ArrayList<People> peopleList = new ArrayList<>();
try {
URL url = new URL(params[0]);
HttpURLConnection httpURLConnection = (HttpURLConnection) url.openConnection();
httpURLConnection.setReadTimeout(40000);
httpURLConnection.setConnectTimeout(50000);
httpURLConnection.setRequestMethod("POST");
httpURLConnection.setRequestProperty("Content-Type", "application/json");
httpURLConnection.setRequestProperty("Accept", "application/json");
httpURLConnection.setDoOutput(true);
JSONObject request = new JSONObject();
request.put("session", params[1]);
String bodyParams = request.toString();
if (DEBUG) {
Log.i(TAG, bodyParams);
}
httpURLConnection.setRequestProperty("Content-Length",
String.valueOf(bodyParams.getBytes().length));
DataOutputStream outputStream = new DataOutputStream(httpURLConnection.getOutputStream());
outputStream.writeBytes(bodyParams);
outputStream.flush();
outputStream.close();
httpURLConnection.connect();
if (httpURLConnection.getResponseCode() == 200) {
Log.i(TAG, "Success");
} else {
Log.i(TAG, "Error Code :" + httpURLConnection.getResponseCode());
}
InputStream inputStream = httpURLConnection.getInputStream();
BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream));
String line;
StringBuilder builder = new StringBuilder();
while ((line = reader.readLine()) != null) {
builder.append(line);
}
Log.i(TAG, "Builder String : " + builder.toString());
JSONObject jsonObject = new JSONObject(builder.toString());
Log.i(TAG, "Response JSON : " + jsonObject.toString());
if (jsonObject.has("responseData")) {
JSONArray responseDataArr = jsonObject.optJSONArray("responseData");
for (int i = 0; i < responseDataArr.length(); i++) {
JSONObject peopleJSON = responseDataArr.optJSONObject(i);
People people = new People();
people.setEmployeeId(peopleJSON.optString("employeeId"));
people.setFirstName(peopleJSON.optString("firstName"));
people.setLastName(peopleJSON.optString("lastName"));
// Log.i("hebsiba ", "People first name" + people.getFirstName() + ", last name is " + people.getLastName()) ;
if((!people.getFirstName().isEmpty()) && (!people.getLastName().isEmpty())) {
peopleList.add(people);
}
if (DEBUG) {
Log.i(TAG, "People " + people.getEmployeeId());
}
}
}
} catch (IOException | JSONException e) {
Log.e(TAG, e.toString());
}
return peopleList;
}
@Override
protected void onPostExecute(List<People> people) {
super.onPostExecute(people);
Collections.sort(people, new Comparator<People>() {
@Override
public int compare(People lhs, People rhs) {
return lhs.getFirstName().compareToIgnoreCase(rhs.getFirstName());
}
});
adapter.addAll(people);
if (DEBUG) {
Log.i(TAG, adapter.getCount() + " ");
}
Log.v(TAG, String.valueOf(people.size()));
progressDialog.dismiss();
}
}
}
这是PeopleAdapter
**PeopleAdapter**
public class PeopleAdapter extends ArrayAdapter<People> implements Filterable {
private PeopleListActivity activity;
private PeopleFilter peopleFilter;
private List<People> peopleList;
private List<People> filteredList;
public PeopleAdapter(Context applicationContext, int people_list_item, List<People> contactList) {
super(applicationContext, people_list_item, contactList);
filteredList = contactList;
getFilter();
}
@Override
public int getCount() {
return filteredList.size();
}
@Override
public People getItem(int i) {
return filteredList.get(i);
}
@Override
public long getItemId(int i) {
return i;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
ViewHolder holder;
People peopleList = getItem(position);
if (convertView == null) {
convertView = LayoutInflater.from(getContext()).inflate(R.layout.people_list_item, null);
holder = new ViewHolder();
holder.firstName = (TextView) convertView.findViewById(R.id.firstName);
holder.lastName = (TextView) convertView.findViewById(R.id.lastName);
convertView.setTag(holder);
} else {
holder = (ViewHolder) convertView.getTag();
}
holder.firstName.setText(peopleList.getFirstName());
holder.lastName.setText(peopleList.getLastName());
return convertView;
}
/**
* Get custom filter
* @return filter
*/
@Override
public Filter getFilter() {
if (peopleFilter == null) {
peopleFilter = new PeopleFilter();
}
return peopleFilter;
}
static class ViewHolder {
TextView firstName;
TextView lastName;
}
private class PeopleFilter extends Filter {
@Override
protected FilterResults performFiltering(CharSequence constraint) {
FilterResults filterResults = new FilterResults();
if (constraint!=null && constraint.length()>0) {
ArrayList<People> tempList = new ArrayList<>();
// search content in friend list
for (People user : peopleList) {
if (user.getFirstName().toLowerCase().contains(constraint.toString().toLowerCase())) {
tempList.add(user);
}
}
filterResults.count = tempList.size();
filterResults.values = tempList;
} else {
filterResults.count = peopleList.size();
filterResults.values = peopleList;
}
return filterResults;
}
/**
* Notify about filtered list to ui
* @param constraint text
* @param results filtered result
*/
@SuppressWarnings("unchecked")
@Override
protected void publishResults(CharSequence constraint, Filter.FilterResults results) {
filteredList = (ArrayList<People>) results.values;
notifyDataSetChanged();
}
}
}
这是PeopleListActivity
**PeopleListActivity**
public class PeopleListActivity extends AppCompatActivity implements SearchView.OnQueryTextListener {
private PeopleListFragment fragment;
private FragmentManager displayFragment;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
Window window = getWindow();
window.addFlags(WindowManager.LayoutParams.FLAG_DRAWS_SYSTEM_BAR_BACKGROUNDS);
window.setStatusBarColor(Color.argb(255, 180, 110, 60));
}
setContentView(R.layout.activity_people);
Toolbar toolbar = (Toolbar) findViewById(R.id.people_toolbar);
setSupportActionBar(toolbar);
toolbar.setNavigationIcon(R.drawable.ic_back_arrow);
getSupportActionBar().setDisplayShowTitleEnabled(false);
toolbar.setNavigationOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent intent = new Intent(PeopleListActivity.this, NavigationActivity.class);
startActivity(intent);
}
});
displayFragment = getSupportFragmentManager();
fragment = new PeopleListFragment();
displayFragment.beginTransaction().add(R.id.people_fragment, fragment).commit();
if (savedInstanceState == null) {
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
MenuInflater inflater = getMenuInflater();
inflater.inflate(R.menu.options_menu, menu);
SearchManager searchManager =(SearchManager) getSystemService(Context.SEARCH_SERVICE);
SearchView searchView =(SearchView) menu.findItem(R.id.search).getActionView();
searchView.setSearchableInfo(searchManager.getSearchableInfo(getComponentName()));
// searchView.setIconifiedByDefault(false);
searchView.setSubmitButtonEnabled(true);
searchView.setOnQueryTextListener(this);
return true;
// return super.onCreateOptionsMenu(menu);
}
@Override
public boolean onQueryTextSubmit(String query) {
return false;
}
@Override
public boolean onQueryTextChange(String newText) {
PeopleAdapter peopleAdapter = (PeopleAdapter) PeopleListFragment.mContactlistView.getAdapter();
peopleAdapter.getFilter().filter(newText);
return true;
}
}
有人可以帮我解决这个问题吗？
答案 0 :(得分：0)
filteredList时，{p> null为getCount()。首先实例化它或确保filteredList有一些内容。
答案 1 :(得分：0)
在创建filteredList
Adapter分配一些值
示例：
public PeopleAdapter(Context applicationContext, int people_list_item, List<People> contactList) {
super(applicationContext, people_list_item, contactList);
filteredList = contactList;
getFilter();
}