android - Cannot touch a external view from inside a AsyncTask... but not always -

i have made asynctask should compile textview. short recap of did. deleted lot of lines hope didn't forget anything.

public class myclass extends relativelayout {         private textview messagetextview;       public myclass(context context) {         super(context);         init(context); }     public myclass(context context, attributeset attrs, int defstyle) {         super(context, attrs, defstyle);         init(context); }     public myclass(context context, attributeset attrs) {         super(context, attrs);         init(context); }       private void init(context context) {         createlayoutcontent();                 run();     }      private void createlayoutcontent (context context) {         this.setlayoutparams(new relativelayout.layoutparams (relativelayout.layoutparams.match_parent, 0));          messageview = new textview(context);         messageview.settext("test");         this.addview(messageview);     }      private void start() {         new asynctask<void, string, void>() {             @override             protected void doinbackground(void... params) {                 try {                     string s_message = "test2";                     messageview.settext(s_message);    **// here error //**                 } catch (malformedurlexception e) {                     e.printstacktrace();                 } catch (ioexception e) {                     e.printstacktrace();                 } catch (jsonexception e) {                     e.printstacktrace();                 }                 return null;             }         }.execute();      }  } 

after this, put object directly in layout:

    <<...>myclass         android:id="@+id/test"         android:layout_width="match_parent"         android:layout_height="wrap_content"      /> 

now problem on some apps works. activity runs, setcontentview() creates ui objects , fine. on other apps, continuously receive error says "only original thread created view hierarchy can touch views."

i error, don't why on apps works fine... more weird, happened me once app on gave error, started working , went error after 2 correct runs!!

this totally weird.

i know maybe details not enough detect error, excuse me this, checked detais think @ , not find notable differences between when works , when not. maybe more expert eyes can detect something, explain or suggest me debug. can 1 me?

thank much.

i'm not sure, why works times. should fail every time. may works, if android system decides run background thread code within ui thread.

here fixes problem: move "touch views" things onpostexcution() or onprogressupdate(). ui meant touched within ui thread. asynctask helps quite conveniently. asynctask's methods doinbackground() running on ui thread.

so, never change views directly doinbackground().

private void start() {     new asynctask<void, string, string>() {         @override         protected string doinbackground(void... params) {             try {                 string s_message = "test2";                 return s_message;             } catch (malformedurlexception e) {                 e.printstacktrace();             } catch (ioexception e) {                 e.printstacktrace();             } catch (jsonexception e) {                 e.printstacktrace();             }             return null;         }          @override         protected void onpostexecute(string s) {             messageview.settext(s);         }     }.execute(); }