android - findViewById usage in View -

i'm struggling problem few days , couldn't find solution problem far. have 2 classes: - startactivity extends activity - timegraphview extends surfaceview

what want achieve add dynamically buttons within timegraphview view (linearlayout). wanted linearlayout inside timegraphview findviewbyid() returns null, , should because call in timegraphview not in root element used setcontentview();

so question how can add button dynamically custom view level view.

and code:

public class startactivity extends activity {      public void oncreate(bundle savedinstancestate) {         super.oncreate(savedinstancestate);         setcontentview(r.layout.time_graph);          linearlayout layout = (linearlayout) this.findviewbyid(r.id.timegraphlayout);         //here can add button it's not want     } } 

and ...

public class timegraphview extends surfaceview implements surfaceholder.callback, runnable {      public timegraphview(context context) {         super(context);     }      public timegraphview(context context, attributeset set) {         super(context, set);     }      public timegraphview(context context, attributeset set, int arg) {         super(context, set, arg);     }      public void run() {         while (run) {             if (something) {                 linearlayout layout = (linearlayout) findviewbyid(r.id.timegraphlayout);                 if (layout != null) {                     button button = new button(context);                     button.settext(text);                     layout.addview(button);                 } else {                     log.e("timegraphview", "timegraphlayout null");                     //and "layout" null , that's problem ;(                 }             }         }     } } 

... , xml

<?xml version="1.0" encoding="utf-8"?> <linearlayout xmlns:android="http://schemas.android.com/apk/res/android"     android:id="@+id/timegraphrootlayout"     android:layout_width="match_parent"     android:layout_height="match_parent"     android:orientation="vertical" >      <horizontalscrollviewa         android:id="@+id/timegraphpanel"         android:layout_width="match_parent"         android:layout_height="wrap_content" >          <linearlayout             android:id="@+id/timegraphlayout"             android:layout_width="wrap_content"             android:layout_height="wrap_content"             android:orientation="horizontal" />     </horizontalscrollview>      <my.package.timegraphview         android:id="@+id/timegraphchart"         android:layout_width="match_parent"         android:layout_height="wrap_content" />  </linearlayout> 

you cannot use in way. if add root element linear layout , reference in addition might work. if want timegraphlayout class though:

 timegraphview layout = (timegraphview) findviewbyid(r.id.timegraphlayout);  setcontentview(layout); 

the original way did not work because timegraphview not linearlayout