title: find button by ID or TAG
body: <p>I created a button programmatically and give it a ID and a Tag. </p>
  
  <pre><code>Button button = new Button(this);
  button.setId(i);
  button.setTag(anotherID);
  </code></pre>
  
  <p>i is a counter.</p>
  
  <p>Now i want to change the background of this button, but i can't find it with </p>
  
  <pre><code>findViewByID(ID)
  </code></pre>
  
  <p>or</p>
  
  <pre><code>findViewWithTag(anotherID)
  </code></pre>
  
  <p>I use for ID and anotherID the values that i created the buttons with, but i only get NullPointerExceptions. I get no ids from a XML file, because i create the buttons programmatically. Did anybody know how i can handle this?</p>