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Method called inside interface method returns null

I created an interface so I can communicate between a dialogue and a fragment.
Goal: When the user selects anything from the dialogue it should display it on a text view.
In this interface, I created an interface method, called in the main activity and passed the value the user selected in the dialogue. Along with the user selected value, in my fragment, I created a method that will set the text view to that value. However, whenever I call that method it always returns null.
I did plenty of testing with logs and found that the values being passed through my method is NOT null, everything seems to work the exact way I want it to which is odd. What confuses me even more, is that this method isn't even running, it immediately returns null before executing the code inside which is really strange to me.
Dialog Code:
public String users_time;
#Override
public Dialog onCreateDialog(Bundle savedInstanceState) {
final String time_options[] = {"10", "20", "30", "40", "50", "60", "70", "80", "90"}; // Since we know how many options there are in the array we use an array instead of an arraylist
AlertDialog.Builder builder = new AlertDialog.Builder(getActivity());
builder.setTitle("Choose the time");
builder.setSingleChoiceItems(time_options, -1, new DialogInterface.OnClickListener() { // check items = what index is auto selected in the dialog, use -1 bc you dont want that
#Override
public void onClick(DialogInterface dialog, int which) { // which = Index in the array
CharSequence time = time_options[which];
Log.i("this" ,"LOG 1 dialogsTime retusn" + time);
listener.onDialogInput(time);
users_time = time_options[which];
int usersTime = Integer.valueOf(users_time);
listener.grabTime(usersTime);
}
});
builder.setPositiveButton("Set Time", new DialogInterface.OnClickListener() { // positive = Ok or continue
#Override
public void onClick(DialogInterface dialog, int which) {
}
})
.setNegativeButton("Cancel", new DialogInterface.OnClickListener() { // Negative = Cancel or stop
#Override
public void onClick(DialogInterface dialog, int which) {
}
});
return builder.create(); // always return this at the end
}
#Override
public void onAttach(Context context) {
super.onAttach(context);
if (context instanceof DiaglogListener) {
listener = (DiaglogListener) context;
}
else {
throw new RuntimeException(context.toString()
+ " must implement DiaglogListener");
}
}
#Override
public void onDetach() {
super.onDetach();
listener = null;
}
}
Main Activity Interface Method:
#Override
public void onDialogInput(CharSequence dialogsTime) {
Fragment1_timer frag1 = new Fragment1_timer();
Log.i("this" ,"LOG 2 runs successfully");
try {
frag1.setDialogTime(dialogsTime);
} catch (Exception e){
Toast.makeText(this, "Null error :/", Toast.LENGTH_SHORT).show();
}
}
Fragment Method:
public void setDialogTime(CharSequence time){
Log.i("this" ,"LOG 3 ran successfully");
text_view_time.setText(time + ":00");
}

You can't use onAttach method for Fragment to DialogFragment communication.
you will have to use "setTargetFragment" & "getTargetFragment" for that.
you can refer this answer. https://stackoverflow.com/a/32323822/9792247

onCreateDialog is called after show?

I am trying to implement custom DialogFragment. But when I try to show it I am getting NullPointerException. Also as I have noticed onCreateDialog is never implictly called.
What is wrong with it. I have read official manual, and followed all steps in it DialogFragment
Here is my code for custom Dialog Fragment
public class UserInputDialogFragment extends DialogFragment {
InputDialogListener mListener;
private EditText mTextEdit;
public UserInputDialogFragment() {
super();
}
// Use this instance of the interface to deliver action events
#Override
public Dialog onCreateDialog(Bundle savedInstanceState) {
AlertDialog.Builder builder = new AlertDialog.Builder(getActivity());
// Get the layout inflater
LayoutInflater inflater = getActivity().getLayoutInflater();
// Inflate and set the layout for the dialog
// Pass null as the parent view because its going in the dialog layout
View mainView = inflater.inflate(R.layout.dialog_input, null);
builder.setView(mainView);
mTextEdit = (EditText) mainView.findViewById(R.id.user_input);
if (mTextEdit==null) {
Log.e("ERROR","Text edit is null");
}
// Add action buttons
builder.setPositiveButton(R.string.ok_btn, new DialogInterface.OnClickListener() {
#Override
public void onClick(DialogInterface dialog, int id) {
mListener.onDialogPositiveClick(UserInputDialogFragment.this,mTextEdit.getText().toString());
}
});
builder.setNegativeButton(R.string.cancel_bnt, new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int id) {
mListener.onDialogNegativeClick(UserInputDialogFragment.this,mTextEdit.getText().toString());
UserInputDialogFragment.this.getDialog().cancel();
}
});
return builder.create();
}
public interface InputDialogListener {
public void onDialogPositiveClick(DialogFragment dialog, String userInput);
public void onDialogNegativeClick(DialogFragment dialog, String userInput);
}
public void showAndAddHint(FragmentManager manager,String tag,String hint) {
this.onCreateDialog(null);
mTextEdit.setHint(hint);
this.show(manager,tag);
}
#Override
public void onAttach(Activity activity) {
super.onAttach(activity);
// Verify that the host activity implements the callback interface
try {
// Instantiate the NoticeDialogListener so we can send events to the host
mListener = (InputDialogListener) activity;
} catch (ClassCastException e) {
// The activity doesn't implement the interface, throw exception
throw new ClassCastException(activity.toString()
+ " must implement InputDialogListener");
}
}
}
And I am trying to show dialog this way.
UserInputDialogFragment userInputDialogFragment = new UserInputDialogFragment();
userInputDialogFragment.showAndAddHint(getFragmentManager(),"Please enter phone number",task.phoneNumber);
And here is NullPointerException mTextEdit is null.
public void showAndAddHint(FragmentManager manager,String tag,String hint) {
this.onCreateDialog(null);
mTextEdit.setHint(hint);
this.show(manager,tag);
}

The showAndAddHint method won't work as written. What you should do instead is:
1 - Set a member variable mHint = hint;
2 - Call show() exactly the way you're doing it now.
3 - Read the member variable mHint in on create dialog and use it to set the edit text hint.
Don't call onCreateDialog explicitly because the show method does that for you when needed.

When creating a button from a Dialog Box

The original code has been deleted, the new working code is shown. The idea behind the code is to create a new textView within a layout that has a custom name to it that the user provides. Previously, a NPE error was happening. This is a fix. Any questions, please feel free to ask.
EDIT: Found the solution
The fix needs to be as followed:
accountEdit = new EditText(this); // accountEdit needs to be a global variable
then within the builder.setPositiveButton
builder.setPositiveButton(R.string.btn_save, new DialogInterface.OnClickListener(){
public void onClick(DialogInterface dInterface, int whichButton)
{
LinearLayout lineLayout = (LinearLayout)findViewById(R.id.linear_layout);
String newAccountName = accountEdit.getText().toString();
newTextView = new TextView( getBaseContext() );
newTextView.setVisibility(View.VISIBLE);
newTextView.setText( newAccountName );
newTextView.setId(id);
newTextView.setTextSize(35);
newTextView.setOnClickListener(new View.OnClickListener() {
public void onClick(View view) {
onClickNew(view);
}
});
newTextView.setOnLongClickListener(new View.OnLongClickListener() {
#Override
public boolean onLongClick(View view) {
Toast.makeText(getBaseContext(), "Testing" , Toast.LENGTH_LONG).show();
return true;
}
});
This will create the button, as well as set the name of the button to the information that is in the EditText within the Dialog Box. Previously, the EditText was from another activity, and was being called wrong, which caused the NPE. Thank you for all the help.

As Wenhui metioned, you call the finViewById inside the onclick listener of the button, so the wrong context is used. Do it like in the following example:
final EditText accountEdit = (EditText)findViewById(R.id.newAccountButton);
final String newAccountName = accountEdit.getText().toString();
final LinearLayout lineLayout = (LinearLayout)findViewById(R.id.linear_layout);
builder.setPositiveButton(R.string.btn_save, new DialogInterface.OnClickListener(){
public void onClick(DialogInterface dInterface, int whichButton)
{
newTextView = new TextView(getBaseContext());
newTextView.setVisibility(View.VISIBLE);
newTextView.setText("Test");
newTextView.setId(id);
newTextView.setTextSize(35);
newTextView.setOnClickListener(new View.OnClickListener() {
public void onClick(View view) {
onClickNew(view);
}
});
lineLayout.addView(newTextView);
id++;
}
});

Dialog box to confirm deletion of row

I'm trying to add a dialog box which will pop up when a user selects a delete button which will delete a specified row. However I can't seem to get the appropriate syntax for the program to compile. The error occurs at this line;
MODULEDATABASE.deleteRow(rowId);
Intent intent = new Intent(this, MyCourses.class);
Any suggestions would be much appreciated.
public class ViewCourse extends Activity implements OnClickListener{
Cursor cursor;
database MODULEDATABASE;
String rowId;
Button deleteModule;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_view_course);
Intent intent = getIntent();
rowId = intent.getStringExtra(MyCourses.TEST);
MODULEDATABASE = new database(ViewCourse.this);
MODULEDATABASE.openToRead(ViewCourse.this);
cursor = MODULEDATABASE.getRow(rowId);
TextView text_modulecode = (TextView)findViewById(R.id.viewModuleCode);
TextView text_modulename = (TextView)findViewById(R.id.viewModuleName);
text_modulecode.setText(cursor.getString(cursor.getColumnIndex(database.KEY_MODULECODE)));
text_modulename.setText(cursor.getString(cursor.getColumnIndex(database.KEY_MODULENAME)));
deleteModule = (Button)findViewById(R.id.deleteButton);
deleteModule.setOnClickListener(this);
}
public void onClick (View deleteModule)
{
Dialog(rowId);
}
public void Dialog (String rowId) {
// Use the Builder class for convenient dialog construction
AlertDialog.Builder builder = new AlertDialog.Builder(this);
builder.setMessage(R.string.confirmDelete)
.setPositiveButton(R.string.confirmDelete, new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int id) {
MODULEDATABASE = new database(ViewCourse.this);
MODULEDATABASE.deleteRow(rowId);
Intent intent = new Intent(this, MyCourses.class);
startActivity(intent);
}
})
.setNegativeButton(R.string.confirmDelete, new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int id) {
}
});
}
}

You don't say what the error is, but I suspect you need to change this line:
Intent intent = new Intent(this, MyCourses.class);
to:
Intent intent = new Intent(ViewCourse.this, MyCourses.class);
(The problem is that at that point in the code, this refers to the anonymous OnClickListener class.)
EDIT - Declare the rowId parameter to the method to be final:
public void Dialog (final String rowId) {
. . .

Cannot refer to a non-final variable db inside an inner class defined in a different method

I'm developing an app for Android but I got stuck on deleting things from my database!
I'm getting an "Cannot refer to a non-final variable db inside an inner class defined in a different method" error! I know what this error means but I can't seem to find a solution to this.
Here is my code
package iwt.ehb.be.capita_selecta;
//my imports
public class RemoveActivity extends Activity {
Context context = this;
public void onCreate(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
setContentView(R.layout.remove_activity);
DBAdapter db = new DBAdapter(this);
db.open();
Cursor c = db.getAllTrips();
if(c.moveToFirst())
{
LinearLayout layout = (LinearLayout) findViewById(R.id.layout_removeTrips);
LinearLayout.LayoutParams lp = new LinearLayout.LayoutParams(LinearLayout.LayoutParams.FILL_PARENT, LinearLayout.LayoutParams.WRAP_CONTENT);
lp.setMargins(5, 5, 5, 5);
do {
Button buttonView = new Button(this);
buttonView.setBackgroundResource(R.layout.btn_blue);
buttonView.setLayoutParams(lp);
buttonView.setText(c.getString(1) + " # " + c.getString(2));
final int id_trip = c.getInt(0);
buttonView.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
System.out.println(id_trip);
AlertDialog.Builder alert = new AlertDialog.Builder(context).setTitle("Attention");
alert.setMessage("Do you wish to delete this trip?");
alert.setIcon(R.drawable.icon);
alert.setPositiveButton("Yes", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int id) {
db.deleteSpecificRecord(id_trip);
}
});
alert.setNegativeButton("No",
new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int id) {
dialog.cancel();
}
});
alert.show();
}
});
layout.addView(buttonView);
} while (c.moveToNext());
}
db.close();
//*******************
//BACK-button
//*******************
Button back = (Button) findViewById(R.id.back);
back.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
Intent intent = new Intent();
setResult(RESULT_OK, intent);
finish();
}
});
}
}
And I'm getting the error at this line of code db.deleteSpecificRecord(id_trip);
If you have any idea on how I can resolve this that would be awsome ;)
Thx
Kevin

The problem is this line:
AlertDialog.Builder alert = new AlertDialog.Builder(context).setTitle("Attention");
context is a variable from the outer class. Variables like these can only be accessed if they are final.
There are a few possible fixes.
The first one is let your activity implement the onclicklistner
Public class RemoveActivity extends Activity implements OnClickListener { ...
buttonView.setOnClickListener(this);
imho the best solution
Another fix is make the variable context make a constructor with the following code:
Public RemoveActivity (){ this.context = this;}
but this is ugly code
i also think changing the line to
AlertDialog.Builder alert = new AlertDialog.Builder(RemoveActivity.this).setTitle("Attention");
would work.

I had the same error . The thing with this is that java treats each function with an independent scope . I see that you have declared the db Adapter object inside the on Create function . Take the declaration and declare it before the on create function ( rather extending the scope ) this should solve the problem . Your code should look like this :)
public class RemoteActivity extends Activity{
DBAdapter db = new DBAdapter(this);
Context context = this;
onCreate () ...