java - Changing text of a TextView throws NullPointer Exception -


i'm following basic tutorial on android website. however, i'm trying change few things fun. instance, instead of creating runtime textview (as in tutorial) within method oncreate(...) of displaymessageactivty class, i've defined static textview in xml layout file because i'd show other things (e.g., static message resulting entered message main screen). so, in corresponding xml file of displaymessageactivty i've defined textview , other stuff as:

[...]  <textview android:id="@+id/dynamic_msg"     android:layout_width="0dp"     android:layout_height="wrap_content"     android:text="ciao"     android:textsize="40dp"     android:layout_below="@id/static_msg"     android:layout_alignparentleft="true"     android:layout_toleftof="@+id/times" />  [...]

then, access textview in following way (oncreate(...) method of displaymessageactivty class):

@override protected void oncreate(bundle savedinstancestate) {     super.oncreate(savedinstancestate);      // message intent     intent intent = getintent();     string message = intent.getstringextra(mainactivity.extra_message);      // here want change content of textview     textview dynamictext = (textview) findviewbyid(r.id.dynamic_msg);     dynamictext.settext(message);      setcontentview(r.layout.activity_display_message);      // button     getactionbar().setdisplayhomeasupenabled(true); }

unfortunately, when press send button in main activity code throws following exception:

java.lang.nullpointerexception: attempt invoke virtual method 'void android.widget.textview.settext(java.lang.charsequence)' on null object reference

i've searched on internet , approach adopted in other tutorials looks quite similar, cannot understand i'm doing wrong. thanks!

the content not set view, findviewbyid return null if before setcontentview.

move setcontentview before findviewbyid , work.


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