title: Attempt to invoke virtual method '...TextView.setText(java.lang.CharSequence)' on a null object reference
body: <p>I'm an German and new in android, so sorry for bad english or silly mistakes...
  I want to edit the text of my TextView.
  Eventhough I've read the problems with my error message, I didn't find a solution...
  I'm receiving the error message in the title due to the following code.
  Why?</p>
  
  <p>Java Code (just the OnCreate Method where it shows up the error)</p>
  
  <pre><code>@Override
  protected void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
  
      TextView t= (TextView)findViewById(R.id.startofweek);
      t.setText("05.09.2016");
  
      setContentView( R.layout.activities);
  }
  </code></pre>
  
  <p>FXML (just the Part of the TextView, originally it is placed in a FrameView)</p>
  
  <pre><code>&lt;TextView
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:textAppearance="?android:attr/textAppearanceMedium"
      android:id="@+id/example"
      android:layout_gravity="left|top"
      android:layout_marginTop="20dp"
      android:layout_marginLeft="70dp"
      android:background="#00ffffff"
      android:textStyle="bold"
      android:textColor="#ffffff"
      android:textSize="20dp" /&gt;
  </code></pre>
  
  <p>Would be happy if someone has a solution for me :)</p>