title: How to setTheme to an activity at runtime? It doesn't work call setTheme before onCreate and setContentView
body: <p>I want <code>setTheme</code> to an activity at runtime, I have search some solutions by google.
  someone said call <code>setTheme</code> before onCreate and setContentView can works, the code section like</p>
  
  <pre><code>public void onCreate(Bundle savedInstanceState) {
      setTheme(android.R.style.Theme_Translucent_NoTitleBar);
      super.onCreate(savedInstanceState);
      ...
      setContentView(...)
  }
  </code></pre>
  
  <p>but it not works, I want to know, is there another solution can setTheme to activity?</p>