NullPointerException when setting onClickListener in a Fragment

Question

I am trying to create a DatePicker dialog that opens when a button in my dialog made from a custom layout is pressed. I have tried many different configurations of code and the result when the button is pressed is always either a NullPointerException or the button does nothing. I am pretty new to android programming but my best guess is that findViewById is not able to find the button because I am working in a Fragment and the content view is not specified. I tried to use setContentView but that wasn't working. Hopefully someone can figure this out and let me know how they did it!

NewTaskDialogFragment.java:

public class NewTaskDialogFragment extends DialogFragment implements
        android.view.View.OnClickListener {
    public int mYear, mMonth, mDay;
    public static final int DIALOG_ID = 0;
    private Button btn;
    private View dialogView;


    public Dialog onCreateDialog(Bundle savedInstanceState) {
        Context context = getActivity();


        AlertDialog.Builder builder = new AlertDialog.Builder(context);


        LayoutInflater inflater = LayoutInflater.from(context);
         dialogView= inflater.inflate(R.layout.new_task_dialog, null);
        builder.setView(dialogView)

        ;
        btn =(Button) dialogView.findViewById(R.id.datePickerDialogButton);
        showDialogOnButtonClick();

        return builder.create();
    }
    public void showDialogOnButtonClick(){



        btn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                getActivity().showDialog(DIALOG_ID);
            }
        });
    }

    private DatePickerDialog.OnDateSetListener dpickerListener
            = new DatePickerDialog.OnDateSetListener() {
        @Override
        public void onDateSet(DatePicker view, int year, int monthOfYear, int dayOfMonth) {
            TextView dateDisplay = (TextView) getActivity().findViewById(R.id.dateDisplayBox);

            mYear = year;
            mMonth = monthOfYear;
            mDay = dayOfMonth;
            dateDisplay.setText(mYear + mMonth + mDay);
        }
    };

    @Override
    protected Dialog onCreateDialog(int id){
        if(id == DIALOG_ID) {
            return new DatePickerDialog(getActivity(), dpickerListener , mYear, mMonth, mDay);
        }else{
            return null;
        }
    }


    @Override
    public void onClick(View view) {

    }
}

Does your `getActivity()` return **null**? – K.Sopheak Nov 18 '16 at 03:12 — K.Sopheak, Nov 18 '16 at 03:12

score 1 · Accepted Answer · answered Nov 18 '16 at 03:22

import android.support.v4.app.Fragment;

public class FooFragment extends Fragment {
    // The onCreateView method is called when Fragment should create its View object hierarchy,
    // either dynamically or via XML layout inflation. 
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup parent, Bundle savedInstanceState) {
        // Defines the xml file for the fragment
        return inflater.inflate(R.layout.fragment_foo, parent, false);
    }

    // This event is triggered soon after onCreateView().
    // Any view setup should occur here.  E.g., view lookups and attaching view listeners.
    @Override
    public void onViewCreated(View view, Bundle savedInstanceState) {
        // Setup any handles to view objects here
        // EditText etFoo = (EditText) view.findViewById(R.id.etFoo);
    }
}

Priya Jagtap · Answer 2 · 2016-11-18T05:35:01.537

1

Try adding btn.setOnClickListener(new View.OnClickListener() {} just below the button initialization in public Dialog onCreateDialog(Bundle savedInstanceState) {}, rather than calling it from function showDialogOnButtonClick(). Calling it from function may returning getActivity() as null. Hope this will help you.

edited Nov 18 '16 at 05:35

answered Nov 18 '16 at 05:27

Priya Jagtap

1,023
13
19

score -1 · Answer 3 · answered Nov 18 '16 at 03:27

You have registered the click listener in the method showDialogOnButtonClick,in the method onClick you have getActivity!This action probably cause the NullPointException,you can print a log!Before getActivity,make sure your fragment is attach to the activity and it is actively!

NullPointerException when setting onClickListener in a Fragment

3 Answers3