Android animate text when calling setText() -

i want animated text fade in , out when changing extending textswitcher in order define once since have many textswitcher objects.

however keep on getting null pointer "java.lang.nullpointerexception android.widget.textswitcher.settext(textswitcher.java:80) when doing :

hometeamtextview.settext("text"); 

i decided extend textswitcher class this:

public class mytextswitcher extends textswitcher{  public mytextswitcher(context context, attributeset attrs) {     super(context, attrs);     // todo auto-generated constructor stub      setinanimation(context,r.anim.fade_in);     setoutanimation(context,r.anim.fade_out); }} 

activity

private mytextswitcher hometeamtextview;  @override protected void oncreate(bundle savedinstancestate) {     super.oncreate(savedinstancestate);     setcontentview(r.layout.activity_main);      hometeamtextview = (mytextswitcher) findviewbyid(r.id.hometeam);     awayscoretextview = (textview) findviewbyid(r.id.awayteamscore);     homescoretextview = (textview) findviewbyid(r.id.hometeamscore);     gamestatustextview = (textview) findviewbyid(r.id.gamestatus);     gameclocktextview = (textview) findviewbyid(r.id.gameclock);     gamestarttextview = (textview) findviewbyid(r.id.gamestart);     gameclocksectiontextview = (textview) findviewbyid(r.id.gameclocksection);      loaddataasynctask loaddatatask = new loaddataasynctask();     loaddatatask.execute(); } 

layout:

  <com.mytextswitcher         android:id="@+id/hometeam"         android:layout_width="wrap_content"         android:layout_height="wrap_content"          /> 

it looks textswitcher common viewswitcher can contain textviews. when call settext() try next view. can find in source: https://android.googlesource.com/platform/frameworks/base/+/refs/heads/master/core/java/android/widget/textswitcher.java, it's null. think must add textview inside textswitcher (or 2 textview working animation).