Change the background color of a pop-up dialog

Question

I wrote android code that shows a pop-up dialog but I want to change the background color from black to white , and then the color of the writing.

This is the dialog's code:

mPrefs = PreferenceManager.getDefaultSharedPreferences(this);

    Boolean welcomeScreenShown = mPrefs.getBoolean(welcomeScreenShownPref, false);

    if (!welcomeScreenShown) {


        String whatsNewText = getResources().getString(R.string.Text);
        new AlertDialog.Builder(this).setMessage(whatsNewText).setPositiveButton(
                R.string.ok, new DialogInterface.OnClickListener(){
            public void onClick(DialogInterface dialog, int which) {
                dialog.dismiss();
            }
        }).show();
        SharedPreferences.Editor editor = mPrefs.edit();
        editor.putBoolean(welcomeScreenShownPref, true);
        editor.commit(); // Very important to save the preference
    }

Answer 1

To expand on @DaneWhite's answer, you don't have to rely on the built-in themes. You can easily supply your own style:

<style name="MyDialogTheme" parent="Theme.AppCompat.Light.Dialog.Alert">
    <item name="android:background">@color/myColor</item>
</style>

and then apply it in the Builder constructor:

Java:

AlertDialog alertDialog = new AlertDialog.Builder(getContext(), R.style.MyDialogTheme)
        ...
        .create();

Kotlin:

var alertDialog = AlertDialog.Builder(context, R.style.MyDialogTheme)
        ...
        .create()

This should work whether you are using android.support.v7.app.AlertDialog or android.app.AlertDialog

This also works better than @DummyData's answer because you don't resize the dialog. If you set window's background drawable you overwrite some existing dimensional information and get a dialog that is not standard width.

If you set background on theme and the set the theme on dialog you'll end up with a dialog that is colored how you want but still the correct width.