Java Can'；无法从AlertDialog中找到Databasehelper

目前，我正在尝试将数据插入SQLite数据库。我已经做到了。但现在我可能遇到了上下文问题

按下按钮后，AlertDialog将打开。之后，您可以将文本放入EditText。现在，用户必须按ok，然后，EditText中的日期需要进入SQLite数据库

问题是“DataBaseHelper_DB DataBaseHelper_DB=new DataBaseHelper_DB（getActivity（））；”始终为空

我怎样才能改变这个

 private void openDialog() {
    Dialog Dialog = new Dialog();
    Dialog.show(getSupportFragmentManager(), "Dialog");
}

__________________________________________________________________________________________________________________

public class Dialog extends AppCompatDialogFragment 
{
private EditText Profile;
Date date;
DpD_DB DpD_DB;

DataBaseHelper_DB DataBaseHelper_DB = new DataBaseHelper_DB(getActivity()); 



@Override
public android.app.Dialog onCreateDialog(@Nullable Bundle savedInstanceState) {
    AlertDialog.Builder builder = new AlertDialog.Builder(getContext());

    LayoutInflater inflater = getActivity().getLayoutInflater();
    View view = inflater.inflate(R.layout.layout_dialog, null);



    builder.setView(view)
            .setTitle("Profile")
            .setNegativeButton("Cancel", new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialog, int which) {

                }
            })
            .setPositiveButton("Ok", new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialog, int which) {
                    String editProfile = Profile.getText().toString();

                    SimpleDateFormat sdf = new SimpleDateFormat("yyyyMMdd");
                    SimpleDateFormat sdfT = new SimpleDateFormat("HHmmss");
                    date = new Date();

                    try {
                        DpD_DB = new DpD_DB(-1, sdf.format(date).toString(), 
                        sdfT.format(date).toString(), editProfile);
                    }
                    catch (Exception e) {
                        e.toString();
                    }

                    DataBaseHelper_DB.addOne(DpD_DB);

                }
            });
    Profile = view.findViewById(R.id.Profile);

    return builder.create();
}

________________________________________________________________________________________________________________

public DataBaseHelper_DB(@Nullable Context Context){
    super(Context, DB_TABLE, null, 1);
}

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尝试为您的对话框实现一个侦听器，如下面的代码所示。在Activity类中，实现listener并使用listeners方法获取文本。希望我清楚

public class Dialog extends AppCompatDialogFragment{

private EditText Profile;
Date date;
DpD_DB DpD_DB;
ProjectDialogListener listener;

DataBaseHelper_DB DataBaseHelper_DB = new DataBaseHelper_DB(getActivity()); 



@Override
public android.app.Dialog onCreateDialog(@Nullable Bundle savedInstanceState) {
    AlertDialog.Builder builder = new AlertDialog.Builder(getContext());

    LayoutInflater inflater = getActivity().getLayoutInflater();
    View view = inflater.inflate(R.layout.layout_dialog, null);



    builder.setView(view)
            .setTitle("Profile")
            .setNegativeButton("Cancel", new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialog, int which) {

                }
            })
            .setPositiveButton("Ok", new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialog, int which) {
                    String editProfile = Profile.getText().toString();

                    SimpleDateFormat sdf = new SimpleDateFormat("yyyyMMdd");
                    SimpleDateFormat sdfT = new SimpleDateFormat("HHmmss");
                    date = new Date();

                    try {
                        DpD_DB = new DpD_DB(-1, sdf.format(date).toString(), 
                        sdfT.format(date).toString(), editProfile);
                    }
                    catch (Exception e) {
                        e.toString();
                    }

                    //DataBaseHelper_DB.addOne(DpD_DB);
                    //Use the listener to get the text
                    listener.applyTexts(Dpd_DB)
                }
            });
    Profile = view.findViewById(R.id.Profile);

    return builder.create();
}



 @Override
  public void onAttach(Context context) {
    super.onAttach(context);
    try {
      listener = (ProjectDialogListener) getActivity();//I am guessing u are using an activity else your the getActivity to getTargetFragment.
    } catch (ClassCastException e) {
      throw new ClassCastException(context.toString() + "must implement ProjectDialogListener");
    }
  }

public interface ProjectDialogListener {
    void applyTexts(String title);
  }

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现在，对话框甚至不再打开。但是你的想法让我想到了另一种解决问题的方法。谢谢大家!@吉比·吉布森很乐意帮忙