Dialog with transparent background in Android

How do I remove the black background from a dialog box in Android. The pic shows the problem.

final Dialog dialog = new Dialog(Screen1.this);
dialog.requestWindowFeature(Window.FEATURE_NO_TITLE);
dialog.setContentView(R.layout.themechanger); 

Add this code

 dialog.getWindow().setBackgroundDrawable(new ColorDrawable(android.graphics.Color.TRANSPARENT));

Or this one instead:

dialog.getWindow().setBackgroundDrawableResource(android.R.color.transparent);

<style name="NewDialog">
    <item name="android:windowFrame">@null</item>
    <item name="android:windowBackground">@android:color/transparent</item>
    <item name="android:windowIsFloating">true</item>
    <item name="android:windowContentOverlay">@null</item>
    <item name="android:windowTitleStyle">@null</item>
    <item name="android:windowAnimationStyle">@android:style/Animation.Dialog</item>
    <item name="android:windowSoftInputMode">stateUnspecified|adjustPan</item>
    <item name="android:backgroundDimEnabled">false</item>
    <item name="android:background">@android:color/transparent</item>
</style>

use in java

Dialog dialog = new Dialog(this, R.style.NewDialog);

I hope help you !