title: setContentView and findViewById
body: <p>After reading some related posts I already know that I have to explicitly call to setContenView before trying to find by id an element into an Activity-View-Hierarchy. I've created an Activity with an inflated view and all works fine. The problem is when I try to set another view to this activity by using the next xml and code:  </p>
  
  <pre><code>&lt;RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
  xmlns:tools="http://schemas.android.com/tools"
  android:layout_width="match_parent"
  android:layout_height="match_parent"
  android:paddingLeft="0dp"
  android:paddingRight="0dp"
  android:paddingTop="0dp"
  android:paddingBottom="0dp"
  android:background="#B12A6D"
  tools:context=".MainActivity"
  android:orientation="vertical"
  &gt;
  
  &lt;LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
      android:orientation="vertical"
      android:layout_width="match_parent"
      android:layout_height="match_parent"
      android:gravity="top"
      android:background="@drawable/bg_purple_500"
      android:layout_margin="0dp"
      &gt;
  
  &lt;GridLayout xmlns:android="http://schemas.android.com/apk/res/android"
          xmlns:tools="http://schemas.android.com/tools"
          android:id="@+id/GridLayout1"
          android:layout_width="wrap_content"
          android:layout_height="0dp"
          android:layout_weight="50"
          android:columnCount="4"
          android:rowCount="4"
          android:orientation="horizontal"
          tools:context=".GridXMLActivity"
          android:layout_gravity="center_horizontal"
          android:layout_marginTop="10dp"
          &gt;
  
           &lt;ImageView
              android:id="@+id/my_bnt"
              android:layout_width="wrap_content"
              android:layout_height="wrap_content"
              android:src="@drawable/icon_new_game"
              android:contentDescription="@string/text"
              android:layout_marginTop="10dp"
              android:layout_marginLeft="20dp"
              android:layout_marginRight="20dp"
              android:layout_marginBottom="10dp"
              /&gt;
  &lt;/GridLayout&gt;
  
  &lt;/LinearLayout&gt;
  
  &lt;/RelativeLayout&gt;
  </code></pre>
  
  <p>code:</p>
  
  <pre><code>public class MainActivity extends ActionBarActivity {
  
  @Override
  protected void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
  
      setContentView(R.layout.activity_main);
  
  }
  
  
  ....
  
  protected void method_triggered_from_UI_thread() {
  
    // Inflate other layout...
    View view = View.inflate(this, R.layout.my_layout, null) ;
    setContentView(view);
    ImageView btn = (ImageView) findViewById(R.id.my_bnt);
    // btn is null...
  
  }
  </code></pre>
  
  <p>I've tried other slight variations:</p>
  
  <pre><code>View mainView = findViewById(android.R.id.content);
  LayoutInflater inflater = LayoutInflater.from(this);
  View view = inflater.inflate(R.layout.my_layout, (ViewGroup) mainView, false)  ;
  setContentView(view);
  ImageView btn = (ImageView) view.findViewById(R.id.my_bnt);
  </code></pre>
  
  <p>And I always get btn == null. What am I doing wrong?</p>
  
  <p>Thx</p>