title: Insert TextView in other XML file than current ContentView
body: <p>I want to insert a TextView into a LinearLayout that's in a different XML file that is being used as layout for a ListView. But it seems that I can't access the LinearLayout that's in the other XML file.</p>
  
  <p>I run a loop that gets category titles, and for each title I wanna create a TextView with the title.</p>
  
  <p><strong>How I insert the TextView</strong></p>
  
  <pre><code>LinearLayout Layout = (LinearLayout) findViewById(R.id.itemDesign); //When debugging I can see "Layout" is just null. itemDesign is also not in main.xml.
  TextView title = new TextView(this);
  title.setText(CatName);
  Layout.addView(title);
  </code></pre>
  
  <p><strong>XML used by ListView "single_list_item.xml"</strong></p>
  
  <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
  &lt;LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
      android:id="@+id/itemDesign"
      android:layout_width="match_parent"
      android:layout_height="match_parent"
      android:orientation="vertical" &gt;
  
      &lt;!-- Name Label --&gt;
      &lt;TextView android:id="@+id/name_label"
          android:layout_width="fill_parent"
          android:layout_height="wrap_content"
          android:textSize="25dip"
          android:textStyle="bold"
          android:paddingTop="10dip"
          android:paddingBottom="10dip"
          android:textColor="#43bd00"/&gt;
      &lt;!-- Description Label --&gt;
      &lt;TextView android:id="@+id/email_label"
          android:layout_width="fill_parent"
          android:layout_height="wrap_content"
          android:textColor="#acacac"/&gt;
  &lt;/LinearLayout&gt;
  </code></pre>