title: Update Android TextView
body: <p>I have an simple android app that I want to write on the display the value of a single field, that belongs to a different class.</p>
  
  <p>Using the simple text view I can write the initial value of the field but I don't know how to update the text on the display whenever the field has changed value. </p>
  
  <p>Btw, it is my first android app so im still lost</p>
  
  <p>Here is my activity code: </p>
  
  <pre><code>public class findIT extends Activity {
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      PositionHolder ph = new PositionHolder();
      TextView tv = new TextView(this);
      setContentView(tv);
      //this.updateText();
      tv.setText("You are at "  + ph.getPosition());
    }
  }
  </code></pre>