add opacity to activity android

1<?xml version="1.0" encoding="utf-8"?>
2<resources>
3  <style name="Theme.Transparent" parent="android:Theme">
4    <item name="android:windowIsTranslucent">true</item>
5    <item name="android:windowBackground">@android:color/transparent</item>
6    <item name="android:windowContentOverlay">@null</item>
7    <item name="android:windowNoTitle">true</item>
8    <item name="android:windowIsFloating">true</item>
9    <item name="android:backgroundDimEnabled">false</item>
10  </style>
11</resources>