请帮助我，我使用导航抽屉和片段。当用户按下登录按钮时，我会检索用户数据并将其发送到片段中的变量。但是调用片段时，片段中的变量值为null。值如何不能为null。下面是代码：
public class RecyclerViewBookingFragment extends Fragment implements DatePickerDialog.OnDateSetListener {
private static final String TAG = RecyclerViewBookingFragment.class.getSimpleName();
private View dialogView;
private LayoutInflater inflater;
private AlertDialog.Builder dialog;
private ProgressDialog pDialog;
private Context context;
private RecyclerView recyclerView;
private SwipeRefreshLayout swipeRefreshLayout;
private RecyclerViewBookingAdapter adapter;
private List<Booking> bookingList = new ArrayList<>();
private static final Helper helper = new Helper();
private EditText editTextRelasi, editTextKapal, editTextAlamatKapal, editTextTanggal, editTexttglPengajuan, editTextKuota, EditTextUserIDPass, editTextUnamePass, editTextPasslama, editTextPassnew;
private String userid, namaRelasi, tanggalPembuatan, namaKapal, tanggalAntri, kuotaBongkar, createdBy, createdDevice, statusBongkar;
private long detailIDuser, groupidx;
public String useridx, usernamex, groupNamex, namaKapalx, alamatKapalx, passwordx;
public RecyclerViewBookingFragment() {
}
@Override
public void onAttach(Context context) {
super.onAttach(context);
this.context = context;
}
@Nullable
@Override
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.booking_recycler_view_fragment, null);
if (getArguments() != null) {
userid = getArguments().getString(KeyContent.KEY_USERID);// ============>>>>>>> this tes get from login activity (NULL VALUE)
}
return view;
}
@Override
public void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
@Override
public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
pDialog = new ProgressDialog(context);
recyclerView = view.findViewById(R.id.recycler_view_booking);
swipeRefreshLayout = view.findViewById(R.id.swipe_refresh_booking);
FloatingActionButton fab = view.findViewById(R.id.fab);
fab.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
pDialog.setMessage("Loading Form ...");
pDialog.show();
entryDialog(0, "", "", "", "", 0);
pDialog.dismiss();
Toast.makeText(context, userid, Toast.LENGTH_SHORT).show(); // ============>>>>>>> this tes get from login activity (NULL VALUE)
}
});
swipeRefreshLayout.setOnRefreshListener(new SwipeRefreshLayout.OnRefreshListener() {
@Override
public void onRefresh() {
getAllBooking(KeyContent.KEY_GET_ALL);
swipeRefreshLayout.setRefreshing(false);
}
});
recyclerView.addOnItemTouchListener(new RecyclerTouchListener(context.getApplicationContext(), recyclerView, new RecyclerTouchListener.ClickListener() {
@Override
public void onClick(View view, int position) {
// if (usernamex.toLowerCase().trim().equals(bookingList.get(position).getNamaRelasi().toLowerCase().trim())) {
entryDialog(bookingList.get(position).getDetailID(),
bookingList.get(position).getNamaRelasi(),
bookingList.get(position).getNamaKapal(),
bookingList.get(position).getTanggalPembuatan(),
bookingList.get(position).getTanggalAntri(),
bookingList.get(position).getKuotaBongkar());
/* } else {
helper.iMessagaseBuilder(context, " !", false);
}*/
}
@Override
public void onLongClick(View view, int position) {
}
}));
getAllBooking(KeyContent.KEY_GET_ALL);
}`
From login Activity ` loginbutton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
String userid = textViewuserid.getText().toString();
String passd = textViewPass.getText().toString();
if (userid.isEmpty()) {
textViewuserid.setError("User ID Tidak Boleh Kosong");
textViewuserid.requestFocus();
return;
}
if (passd.isEmpty()) {
textViewPass.setError("Password Harus Diisi");
textViewPass.requestFocus();
return;
}
_GetUserLogin(userid, passd, getDev.getDeviceName(), versionName);
Bundle bundle = new Bundle();
bundle.putString(KeyContent.KEY_USERID,"WAI");
RecyclerViewBookingFragment fragment = new RecyclerViewBookingFragment();
fragment.setArguments(bundle);
getSupportFragmentManager().beginTransaction().add(android.R.id.content, fragment).commit();
}
});`
in MainNavigationDrawer ` private void setupViewPager(ViewPager viewPager) {
ViewPagerAdapter adapter = new ViewPagerAdapter(getSupportFragmentManager());
adapter.addFrag(new RecyclerViewBookingFragment(), "List Antrian"); //=====================================>> calling Fragment
adapter.addFrag(new GridViewFragment(), "GridView");
viewPager.setAdapter(adapter);
}
答案 0 :(得分：0)
片段使用接口进行通信， FragmentA 可以通过创建定义方法的内部接口来与 FragmentB 进行通信。调用 活动 必须实现。 FragmentB 的功能相同，但其方法可以是在 FragmentA 将数据传递给活动后从活动中获取数据。下面是一个示例：
public class FragmentA extends Fragment{
private Listener mListener;
public interface Listener{
void setUser(String user);
void setPassword(String password);
}
@Override
public void onAttach(Context context) {
super.onAttach(context);
listener = (Listener) context;
}
public void someMethod(String user, String password){
mListener.setUser(user);
mListener.setPassword(password);
}
}
FragmentB 同样适用，它将从活动中选择传递的数据。
public class FragmentB extends Fragment{
private Listener mListener;
private String user;
private String password;
public interface Listener{
String getUser();
String getPassword();
}
@Override
public void onAttach(Context context) {
super.onAttach(context);
mListener = (Listener) context;
}
public void someMethod(){
user = mListener.getUser();
password = mListener.getUser();
// use the data in some way
}
}
该活动还必须实现这些接口以最终确定通信管道。
public class MainActivity extends Activity implements FragmentA.Listener, FragmentB.Listener{
private String user;
private String password;
public String getUser() {
return user;
}
public void setUser(String user) {
this.user = user;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
// the rest of the code that creates the fragments
}
希望对您有帮助。