NPE in ShareUtils in some cases after application minimized

[Eugene Popovich]

It happens when share on twitter or facebook. Dialog is not appearing and NPE occurs. Reproduces this on Android 4.2 emulator

    at com.trovebox.android.app.share.ShareUtils$TwitterShareRunnable.run(ShareUtils.java:153)
    at com.trovebox.android.app.twitter.TwitterUtils.runAfterTwitterAuthentication(TwitterUtils.java:268)
    at com.trovebox.android.app.twitter.TwitterUtils.runAfterTwitterAuthentication(TwitterUtils.java:219)
    at com.trovebox.android.app.PhotoDetailsActivity$PhotoDetailsUiFragment.shareActivePhotoViaTwitter(PhotoDetailsActivity.java:317)
    at com.trovebox.android.app.PhotoDetailsActivity$PhotoDetailsUiFragment$3.run(PhotoDetailsActivity.java:275)
    at com.trovebox.android.app.share.ShareUtils.confirmPrivatePhotoSharingAndRun(ShareUtils.java:79)
    at com.trovebox.android.app.PhotoDetailsActivity$PhotoDetailsUiFragment.confirmPrivatePhotoSharingAndRun(PhotoDetailsActivity.java:344)
    at com.trovebox.android.app.PhotoDetailsActivity$PhotoDetailsUiFragment.onOptionsItemSelected(PhotoDetailsActivity.java:271)
    at android.support.v4.app.Watson.onMenuItemSelected(Watson.java:126)
    at com.actionbarsherlock.ActionBarSherlock.callbackOptionsItemSelected(ActionBarSherlock.java:603)
    at com.actionbarsherlock.internal.ActionBarSherlockNative.dispatchOptionsItemSelected(ActionBarSherlockNative.java:93)
    at org.holoeverywhere.addon.AddonSherlock$AddonSherlockA.onMenuItemSelected(AddonSherlock.java:98)
    at org.holoeverywhere.app.Activity$10.action(Activity.java:306)
    at org.holoeverywhere.app.Activity$10.action(Activity.java:1)
    at org.holoeverywhere.addon.IAddonAttacher$AddonCallback.performAction(IAddonAttacher.java:24)
    at org.holoeverywhere.addon.IAddonBasicAttacher.performAddonAction(IAddonBasicAttacher.java:115)
    at org.holoeverywhere.app.Activity.performAddonAction(Activity.java:528)
    at org.holoeverywhere.app.Activity.onMenuItemSelected(Activity.java:303)
    at com.android.internal.policy.impl.PhoneWindow.onMenuItemSelected(PhoneWindow.java:980)
    at com.android.internal.view.menu.MenuBuilder.dispatchMenuItemSelected(MenuBuilder.java:735)
    at com.android.internal.view.menu.SubMenuBuilder.dispatchMenuItemSelected(SubMenuBuilder.java:81)
    at com.android.internal.view.menu.MenuItemImpl.invoke(MenuItemImpl.java:149)
    at com.android.internal.view.menu.MenuBuilder.performItemAction(MenuBuilder.java:874)
    at com.android.internal.view.menu.MenuPopupHelper.onItemClick(MenuPopupHelper.java:156)
    at android.widget.AdapterView.performItemClick(AdapterView.java:298)
    at android.widget.AbsListView.performItemClick(AbsListView.java:1100)
    at android.widget.AbsListView$PerformClick.run(AbsListView.java:2749)
    at android.widget.AbsListView.onTouchEvent(AbsListView.java:3435)
    at android.view.View.dispatchTouchEvent(View.java:7246)
    at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2168)
    at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1903)
    at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2174)
    at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1917)
    at android.widget.PopupWindow$PopupViewContainer.dispatchTouchEvent(PopupWindow.java:1592)
    at android.view.View.dispatchPointerEvent(View.java:7426)
    at android.view.ViewRootImpl.deliverPointerEvent(ViewRootImpl.java:3220)
    at android.view.ViewRootImpl.deliverInputEvent(ViewRootImpl.java:3165)
    at android.view.ViewRootImpl.doProcessInputEvents(ViewRootImpl.java:4292)
    at android.view.ViewRootImpl.enqueueInputEvent(ViewRootImpl.java:4271)
    at android.view.ViewRootImpl$WindowInputEventReceiver.onInputEvent(ViewRootImpl.java:4363)
    at android.view.InputEventReceiver.dispatchInputEvent(InputEventReceiver.java:179)
    at android.os.MessageQueue.nativePollOnce(Native Method)
    at android.os.MessageQueue.next(MessageQueue.java:125)
    at android.os.Looper.loop(Looper.java:124)
    at android.app.ActivityThread.main(ActivityThread.java:5041)
    at java.lang.reflect.Method.invokeNative(Native Method)
    at java.lang.reflect.Method.invoke(Method.java:511)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
    at dalvik.system.NativeStart.main(Native Method)

java.lang.NullPointerException
    at com.trovebox.android.app.share.ShareUtils$FacebookShareRunnable.run(ShareUtils.java:185)
    at com.trovebox.android.app.facebook.FacebookUtils.runAfterFacebookAuthentication(FacebookUtils.java:171)
    at com.trovebox.android.app.facebook.FacebookUtils.runAfterFacebookAuthentication(FacebookUtils.java:158)
    at com.trovebox.android.app.PhotoDetailsActivity$PhotoDetailsUiFragment.shareActivePhotoViaFacebook(PhotoDetailsActivity.java:306)
    at com.trovebox.android.app.PhotoDetailsActivity$PhotoDetailsUiFragment$4.run(PhotoDetailsActivity.java:286)
    at com.trovebox.android.app.share.ShareUtils.confirmPrivatePhotoSharingAndRun(ShareUtils.java:79)
    at com.trovebox.android.app.PhotoDetailsActivity$PhotoDetailsUiFragment.confirmPrivatePhotoSharingAndRun(PhotoDetailsActivity.java:344)
    at com.trovebox.android.app.PhotoDetailsActivity$PhotoDetailsUiFragment.onOptionsItemSelected(PhotoDetailsActivity.java:282)
    at android.support.v4.app.Watson.onMenuItemSelected(Watson.java:126)
    at com.actionbarsherlock.ActionBarSherlock.callbackOptionsItemSelected(ActionBarSherlock.java:603)
    at com.actionbarsherlock.internal.ActionBarSherlockNative.dispatchOptionsItemSelected(ActionBarSherlockNative.java:93)
    at org.holoeverywhere.addon.AddonSherlock$AddonSherlockA.onMenuItemSelected(AddonSherlock.java:98)
    at org.holoeverywhere.app.Activity$10.action(Activity.java:306)
    at org.holoeverywhere.app.Activity$10.action(Activity.java:1)
    at org.holoeverywhere.addon.IAddonAttacher$AddonCallback.performAction(IAddonAttacher.java:24)
    at org.holoeverywhere.addon.IAddonBasicAttacher.performAddonAction(IAddonBasicAttacher.java:115)
    at org.holoeverywhere.app.Activity.performAddonAction(Activity.java:528)
    at org.holoeverywhere.app.Activity.onMenuItemSelected(Activity.java:303)
    at com.android.internal.policy.impl.PhoneWindow.onMenuItemSelected(PhoneWindow.java:1133)
    at com.android.internal.view.menu.MenuBuilder.dispatchMenuItemSelected(MenuBuilder.java:735)
    at com.android.internal.view.menu.SubMenuBuilder.dispatchMenuItemSelected(SubMenuBuilder.java:81)
    at com.android.internal.view.menu.MenuItemImpl.invoke(MenuItemImpl.java:149)
    at com.android.internal.view.menu.MenuBuilder.performItemAction(MenuBuilder.java:874)
    at com.android.internal.view.menu.MenuPopupHelper.onItemClick(MenuPopupHelper.java:156)
    at android.widget.AdapterView.performItemClick(AdapterView.java:298)
    at android.widget.AbsListView.performItemClick(AbsListView.java:1110)
    at android.widget.AbsListView$PerformClick.run(AbsListView.java:2906)
    at android.widget.AbsListView$1.run(AbsListView.java:3735)
    at android.os.Handler.handleCallback(Handler.java:615)
    at android.os.Handler.dispatchMessage(Handler.java:92)
    at android.os.Looper.loop(Looper.java:137)
    at android.app.ActivityThread.main(ActivityThread.java:4911)
    at java.lang.reflect.Method.invokeNative(Native Method)
    at java.lang.reflect.Method.invoke(Method.java:511)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:790)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:557)
    at dalvik.system.NativeStart.main(Native Method)

[Eugene Popovich]

Steps to reproduce.
Open photo details
close and immediately open it again
then try to share photo via twitter or facebook. NPE occurs

It happens because of 2 instances onf fragment are in memory at the same time. One is destroyin and one is creating. And destroying fragment nullify currentInstance variable