When you use Theme.AppCompat in your application you can use FullScreenTheme by adding the code below to styles.
<style name="Theme.AppCompat.Light.NoActionBar.FullScreen" parent="@style/Theme.AppCompat.Light.NoActionBar">
<item name="android:windowNoTitle">true</item>
<item name="android:windowActionBar">false</item>
<item name="android:windowFullscreen">true</item>
<item name="android:windowContentOverlay">@null</item>
</style>
and also mention in your manifest file.
<activity
android:name=".activities.FullViewActivity"
android:theme="@style/Theme.AppCompat.Light.NoActionBar.FullScreen"
/>