-2
我得到了在一個listview中單擊的員工行，並將其傳回給MainActivity。然後我試圖將它傳遞給另一個適配器，它將更新其ListView並添加用戶點擊的那一行。我將該員工（可能不是最好的，因爲他們已經在數據庫中有一行）添加到數據庫。然後我創建一個遊標，抓住這一行並嘗試將遊標更改爲topAdapter（我試圖更新的listView適配器）。發送光標添加至另一個列表視圖
我在得到NullPointerException異常topAdapter.changeCursor(clcikedEmployee):
我不認爲創建一個新的TopListCursorAdapter會工作，我不希望創建一個新的，只是更新和新行添加到現有的列表是在裏面。我知道e不是null，因爲當我將它打印到控制檯時，我正確地獲取了點擊用戶的數據。只是無法將它傳遞給TopAdapter以將行添加到現有的列表視圖。
是否可以傳遞給TopFragment並從那裏更新TopListCursorAdapter以將新行添加到列表中？
主要活動
public class MainActivity extends FragmentActivity implements BottomListViewAdapter.BottomListClickListener {
private ProgressBar mProgressBar;
EmployeeDBHandler dbHandler;
private TopListCursorAdapter topAdapter;
private BottomListViewAdapter bottomAdapter;
private ArrayList<Employee> mEmployee;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mProgressBar = (ProgressBar) findViewById(R.id.progressBar);
dbHandler = new EmployeeDBHandler(getApplicationContext());
mProgressBar.setVisibility(View.VISIBLE);
getXMLData();
//GUI for seeing android SQLite Database in Chrome Dev Tools
Stetho.InitializerBuilder inBuilder = Stetho.newInitializerBuilder(this);
inBuilder.enableWebKitInspector(Stetho.defaultInspectorModulesProvider(this));
Stetho.Initializer in = inBuilder.build();
Stetho.initialize(in);
}
public void getXMLData() {
OkHttpClient client = getUnsafeOkHttpClient();
Request request = new Request.Builder()
.url(getString(R.string.API_FULL_URL))
.build();
client.newCall(request).enqueue(new Callback() {
@Override
public void onFailure(Call call, IOException e) {
e.printStackTrace();
}
@Override
public void onResponse(Call call, final Response response) throws IOException {
final String responseData = response.body().string();
final InputStream stream = new ByteArrayInputStream(responseData.getBytes());
final XMLPullParserHandler parserHandler = new XMLPullParserHandler();
final ArrayList<Employee> employees = (ArrayList<Employee>) parserHandler.parse(stream);
for (Employee e : employees) {
dbHandler.addEmployee(e);
}
runOnUiThread(new Runnable() {
@Override
public void run() {
mProgressBar.setVisibility(View.GONE);
displayTopList();
displayBottomList();
}
});
}
});
}
public void displayTopList() {
FragmentTransaction fragmentTransaction = getSupportFragmentManager().beginTransaction();
fragmentTransaction.replace(R.id.topFragment, new TopFragment());
fragmentTransaction.commit();
}
public void displayBottomList() {
FragmentTransaction fragmentTransaction = getSupportFragmentManager().beginTransaction();
fragmentTransaction.replace(R.id.bottomFragment, new BottomFragment());
fragmentTransaction.commit();
}
@Override
public void onBottomListClick(Employee e) {
dbHandler.addEmployee(e);
Log.i("EMPLOYEE", e.toString());
TopFragment topFragment = (TopFragment) getSupportFragmentManager().findFragmentById(R.id.topFragment);
SQLiteDatabase db = dbHandler.getWritableDatabase();
final Cursor clickedEmployee = db.rawQuery("SELECT * FROM " + "employees" + " WHERE " +
"Employee_number" + "=" + e.getEmployee_number(), null);
// change the adapter's Cursor
topFragment.update(clickedEmployee);
}
}
TopFragment
public class TopFragment extends Fragment {
public Cursor mTopCursor;
EmployeeDBHandler dbHandler;
@Nullable
@Override
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_top_list, container, false);
String table = "employees";
int mStartingEmployeeID = 3500075;
dbHandler = new EmployeeDBHandler(getContext());
SQLiteDatabase db = dbHandler.getWritableDatabase();
mTopCursor = db.rawQuery("SELECT * FROM " + table + " WHERE " + "Employee_number" + "=" + mStartingEmployeeID, null);
ListView mTopListView = (ListView) view.findViewById(R.id.mTopList);
TopListCursorAdapter topAdapter = new TopListCursorAdapter(getContext(), mTopCursor);
mTopListView.setAdapter(topAdapter);
return view;
}
public void update(Cursor cursor) {
MergeCursor mergeCursor = new MergeCursor(new Cursor[]{
mTopCursor, cursor });
}
}
底部片段
public class BottomFragment extends Fragment {
public Cursor mBottomCursor;
EmployeeDBHandler dbHandler;
@Nullable
@Override
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_bottom_list, container, false);
dbHandler = new EmployeeDBHandler(getContext());
SQLiteDatabase db = dbHandler.getWritableDatabase();
String table = "employees";
int mStartingEmployeeID = 3500075;
mBottomCursor = db.rawQuery("SELECT * FROM " + table + " WHERE " +
"Employee_number" + "!=" + mStartingEmployeeID + " AND " +
"Manager_employee_number" + "=" + mStartingEmployeeID + " ORDER BY " +
"Last_name" + " ASC", null);
ListView mBottomListView = (ListView) view.findViewById(android.R.id.list);
BottomListViewAdapter mBottomAdapter = new BottomListViewAdapter(getContext(), mBottomCursor);
mBottomListView.setAdapter(mBottomAdapter);
return view;
}
}
您還沒有在上面的snipet中的topAdapter中設置任何值（然後是NPE？） – crgarridos
NPE？如果我將它分配給新的TopListCursorAdapter，我不會得到null點，但沒有任何反應。 –
NPE：NullPointerException。 – crgarridos