Android Dim Background of Custom Dialog - android-xml

Question

As titled, I cannot seem to be able to dim the background of the custom dialog box I have made. Countless solutions online mention the last 3 lines of code in the first snippet below, this has made no impact on the UI of the dialog box.
See the following code:
Dialog dialog = new Dialog(MainActivity.this);
dialog.requestWindowFeature(Window.FEATURE_NO_TITLE);
dialog.setContentView(R.layout.dialog);
TextView textView = (TextView) dialog.findViewById(R.id.textView);
textView.setText("Custom Text Example");
dialog.show();
WindowManager.LayoutParams layoutParams = dialog.getWindow().getAttributes();
layoutParams.dimAmount = .7f;
dialog.getWindow().setAttributes(layoutParams);
The layout xml file for the custom dialog is as follows:
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/progressDialogCustom"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#drawable/dialog_black"
android:orientation="horizontal"
android:padding="10dp" >
<ProgressBar
android:id="#+id/progressBar1"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />
<TextView
android:id="#+id/textView"
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:gravity="center_vertical"
android:textColor="#android:color/white"
android:text="Updating Profile . . ." />
</LinearLayout>
The #drawable/dialog_black file is as follows:
<shape xmlns:android="http://schemas.android.com/apk/res/android"
android:shape="rectangle" >
<solid android:color="#android:color/background_dark" />
<corners
android:bottomLeftRadius="7dp"
android:bottomRightRadius="7dp"
android:topLeftRadius="7dp"
android:topRightRadius="7dp" />
<stroke
android:width="1px"
android:color="#android:color/darker_gray" />
<padding
android:bottom="5dp"
android:left="5dp"
android:right="5dp"
android:top="5dp" />
</shape>

Answer 1

Have you tried adding:
getWindow().addFlags(WindowManager.LayoutParams.FLAG_DIM_BEHIND);
dimAmount is ignored unless this flag is present.