<style name="AlertDialogCustom" parent="@android:style/Theme.Dialog">
<item name="android:textColor">@color/White</item>
<item name="android:textStyle">bold</item>
<item name="android:headerDividersEnabled">true</item>
<item name="android:typeface">normal</item>
<item name="android:background">@color/colorPrimaryDark</item>
</style>
AlertDialog.Builder builder = new AlertDialog.Builder(new ContextThemeWrapper(this, R.style.AlertDialogCustom));