android - Modifying TextView crashes program -

so i've defined layout in xml:

<linearlayout xmlns:android="http://schemas.android.com/apk/res/android"     android:layout_width="fill_parent"     android:layout_height="fill_parent"     android:orientation="vertical"     android:gravity="center">      <textview         android:id="@+id/char_name"         android:layout_width="fill_parent"         android:layout_height="fill_parent"/>  </linearlayout>  

but when try change in java program crashes.

public class displaymessageactivity extends activity {      @suppresslint("newapi")     @override     protected void oncreate(bundle savedinstancestate) {     super.oncreate(savedinstancestate);      textview charname = (textview) findviewbyid(r.id.char_name);     charname.settext("bob");     setcontentview(r.layout.displayname);      } } 

my app compiles , runs, when switches activity crashes. if set text in xml file works fine.

you haven't set content activity. add following in oncreate:

protected void oncreate(bundle savedinstancestate) {     super.oncreate(savedinstancestate);     setcontentview(r.layout.your_layout);      textview charname = (textview) findviewbyid(r.id.char_name);     charname.settext("bob"); } 

where your_layout.xml xml file containing textview id char_name.

note: should set content before initializing textview charname.