如何获得自定义AlertDialog的价值

Question

我创建了一个自定义AlertDialog，并希望保存用户设置的值。但是我无法访问它们，因为Attempt to invoke virtual method 'android.text.Editable android.widget.EditText.getText()' on a null object reference。

我在HomeFragment，我创建了AlertDialog并设置了布局。我是这样做的：

public class HomeFragment extends Fragment implements CustomDialog.CustomDialogListener {
private HomeViewModel homeViewModel;
private View root;
public View onCreateView(@NonNull final LayoutInflater inflater,
final ViewGroup container, Bundle savedInstanceState) {
homeViewModel =
ViewModelProviders.of(this).get(HomeViewModel.class);
root = inflater.inflate(R.layout.fragment_home, container, false);
final TextView textView = root.findViewById(R.id.text_home);
homeViewModel.getText().observe(getViewLifecycleOwner(), new Observer<String>() {
@Override
public void onChanged(@Nullable String s) {
textView.setText(s);
}
});
Button btn_add_apero = (Button) root.findViewById(R.id.btn_add_apero);
btn_add_apero.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
AlertDialog.Builder builder = new AlertDialog.Builder(root.getContext());
builder.setTitle("Super un nouvel apéro !");
final EditText name_apero = (EditText)root.findViewById(R.id.edit_apero);
final EditText date_apero = (EditText)root.findViewById(R.id.edit_date);
builder.setView(inflater.inflate(R.layout.layout_dialog, null))
// Add action buttons
.setPositiveButton(R.string.text_add, new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int id) {
LaperoDatabase db = Room.databaseBuilder(root.getContext(),
LaperoDatabase.class, "lapero_db").allowMainThreadQueries().build();
AperoDao dbApero = db.getAperoDao();
Apero new_apero = new Apero(name_apero.getText().toString(), date_apero.getText().toString());
dbApero.insert(new_apero);
}
})
.setNegativeButton(R.string.text_cancel, new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int id) {
dialog.cancel();
}
});
builder.show();
}
});
return root;
}

在我的layout_dialog.xml中，我设置了2 EditText:

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:padding="16dp">
<EditText
android:id="@+id/edit_apero"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:hint="@string/edit_apero" />
<EditText
android:id="@+id/edit_date"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_below="@id/edit_apero"
android:layout_alignParentStart="true"
android:hint="@string/edit_date"
android:layout_alignParentLeft="true" />
</RelativeLayout>  

如何获取这两个字段中的值？

Answer 1

我注意到的第一件事是，您使用root来查找对话框视图，但root指向您的片段布局。root = inflater.inflate(R.layout.fragment_home, container, false);

在引用其资源id之前，请先膨胀对话框布局。

AlertDialog.Builder builder = new AlertDialog.Builder(getActivity());
View inflater = getLayoutInflater().inflate(R.layout.layout_dialog, null);
builder.setView(inflater);

然后将root更改为inflater，以便引用对话框布局中的视图

final EditText name_apero = (EditText)inflater.findViewById(R.id.edit_apero);
final EditText date_apero = (EditText)inflater.findViewById(R.id.edit_date);

完整代码

Button btn_add_apero = (Button) root.findViewById(R.id.btn_add_apero);
btn_add_apero.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
View inflater = getLayoutInflater().inflate(R.layout.layout_dialog, null);
AlertDialog.Builder builder = new AlertDialog.Builder(getActivity());
builder.setView(inflater);
builder.setTitle("Super un nouvel apéro !");
final EditText name_apero = (EditText)inflater.findViewById(R.id.edit_apero);
final EditText date_apero = (EditText)inflater.findViewById(R.id.edit_date);
// Add action buttons
builder.setPositiveButton(R.string.text_add, new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int id) {
LaperoDatabase db = Room.databaseBuilder(root.getContext(),
LaperoDatabase.class, "lapero_db").allowMainThreadQueries().build();
AperoDao dbApero = db.getAperoDao();
Apero new_apero = new Apero(name_apero.getText().toString(), date_apero.getText().toString());
dbApero.insert(new_apero);
}
})
builder.setNegativeButton(R.string.text_cancel, new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int id) {
dialog.cancel();
}
});
builder.show();
}
});