Unexpected NullpointExpection inside a setter

Question

I'm trying to do a simple operation: click a button and show a custom DialogFragment, but I'm getting a NullPointExpection and I can't figure out why.

mAlertDialog.java:

public class mAlertDialog extends DialogFragment {

    TextView title;

    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.dialog_invalid_time, container, false);
        title = (TextView)view.findViewById(R.id.titleText);
        return view;
    }

    public void setTheTitle(String title) {
        this.title.setText(title);
    }
}

Showing mAlertDialog:

mAlertDialog dialog = new mAlertDialog();
dialog.setTheTitle(getActivity().getString(R.string.invalidTimeTitle));
dialog.show(fm, "InvalidTime");

Error message:

java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.TextView.setText(java.lang.CharSequence)' on a null object reference
    at m.inschool8.Objects.mAlertDialog.setTheTitle(mAlertDialog.java:20)
    at m.inschool8.bSubjects.Fragment_Subjects$55.onClick(Fragment_Subjects.java:2654)
    at android.view.View.performClick(View.java:4780)
    at android.view.View$PerformClick.run(View.java:19866)
    at android.os.Handler.handleCallback(Handler.java:739)
    at android.os.Handler.dispatchMessage(Handler.java:95)
    at android.os.Looper.loop(Looper.java:135)
    at android.app.ActivityThread.main(ActivityThread.java:5254)
    at java.lang.reflect.Method.invoke(Native Method)
    at java.lang.reflect.Method.invoke(Method.java:372)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)

score 0 · Answer 1 · answered Jun 06 '16 at 01:03

0

Your title is null until the DialogFragment is shown causing onCreateView to kick-in. Hence change the order as below:

mAlertDialog dialog = new mAlertDialog();
dialog.show(fm, "InvalidTime");
dialog.setTheTitle(getActivity().getString(R.string.invalidTimeTitle));

answered Jun 06 '16 at 01:03

waqaslam

67,549
16
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That didn't work, same error – John Sardinha Jun 06 '16 at 01:08
what's the exception stack ? – waqaslam Jun 06 '16 at 01:10
The printed error in the log is `Attempt to invoke virtual method 'void android.widget.TextView.setText(java.lang.CharSequence)' on a null object reference` although I don't fully understand how to correctly print in the log, I did `catch (Exception e) {Log.e(TAG, e.toString()); }` – John Sardinha Jun 06 '16 at 01:40

score 0 · Accepted Answer · answered Jun 06 '16 at 01:29

0

The title is still null when you are calling

mAlertDialog dialog = new mAlertDialog();
dialog.setTheTitle(getActivity().getString(R.string.invalidTimeTitle));

so what you can do is

public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.dialog_invalid_time, container, false);
        title = (TextView)view.findViewById(R.id.titleText);
        setTheTitle(getActivity().getString(R.string.invalidTimeTitle));

        return view;
    }

// call it

mAlertDialog dialog = new mAlertDialog();
dialog.show(fm, "InvalidTime");

answered Jun 06 '16 at 01:29

Scary Wombat

44,617
6
35
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Yes I could do that but I may want to use the same DialogFragment in the future with a diffrent title – John Sardinha Jun 06 '16 at 01:41
then you could store the `titleString` as a class field and the call for its value from `onCreateView` – Scary Wombat Jun 06 '16 at 01:55

Unexpected NullpointExpection inside a setter

2 Answers2