Apply Theme in Android

In Android SDK so many  predefine themes are theier, you can change the theme by adding a code in the file AndroidManifest.xml in your Project.

Inside Application tag to take effect on whole Application:

<application android:icon="@drawable/icon" android:label="@string/app_name"
 android:theme="@android:style/Theme.Black"
 >

Inside Activity tag to take effect on individual Activity:

  <activity android:name=".TestThemeActivity"
              android:label="@string/app_name"
              android:theme="@android:style/Theme.Light"
              >