DialogFragment.dismiss crashing with NullPointerException

Question

I'm doing some background work and showing a DialogFragment while I do that. Once my work is done and the relevant callback is invoked, I dismiss the dialog. When I do, I get a crash caused by a NPE in the android source, here:

void dismissInternal(boolean allowStateLoss) {         if (mDialog != null) {             mDialog.dismiss();             mDialog = null;         }         mRemoved = true;         if (mBackStackId >= 0) {             getFragmentManager().popBackStack(mBackStackId,                     FragmentManager.POP_BACK_STACK_INCLUSIVE);             mBackStackId = -1;         } else {             FragmentTransaction ft = getFragmentManager().beginTransaction();             ft.remove(this);             if (allowStateLoss) {                 ft.commitAllowingStateLoss();             } else {                 ft.commit();             }         }     } 

specifically at the line: FragmentTransaction ft = getFragmentManager().beginTransaction();

Answer 1

This may also occur when you call dismiss() before you have called show() like Sogger said.

After Dialog object is constructed but before dialog is not showed, if (mDialog != null) can be passed and NullPointerException will occur.

When you check if mDialog is null or not,

if (mDialog != null) {     mDialog.dismiss();     mDialog = null; } 

Add more conditions like below,

if ((mDialog != null) && mDialog.isAdded() && mDialog.isResumed()) {     mDialog.dismiss();     mDialog = null; } 

I think that mDialog.isAdded() condition might be enough...

Answer 2

Simplest solution is to check "getFragmentManager()" for "null" before calling "dismiss()" method. Also you can extend "DialogFragment" class and override method "dismiss()" to check it there:

@Override public void dismiss() {     if (getFragmentManager() != null) super.dismiss(); }