I know it's very old question but this will help out surely to someone who is using AppCompatActivity or ActionBarActivity. If you are setting a dialog to your activity or say DialogActivity then also the below will work!
dialog = new Dialog(ActivityName.this);
dialog .setCancelable(false);
dialog .setContentView(R.layout.dialog_layout);
Window window = dialog.getWindow();
if(window != null){
window.addFlags(WindowManager.LayoutParams.FLAG_DIM_BEHIND);
window.setDimAmount(0.5f);
//If you are setting a dialog activity
DisplayMetrics displayMetrics = new DisplayMetrics();
getWindowManager().getDefaultDisplay().getMetrics(displayMetrics);
Double dialogWidth = displayMetrics.widthPixels * 0.50;
window.setLayout(dialogWidth.intValue(),
WindowManager.LayoutParams.WRAP_CONTENT); //Setting it cover half of the screen width
}
dialog.show();
Just before you dismiss the dialog,
dialog.getWindow().clearFlags(WindowManager.LayoutParams.FLAG_DIM_BEHIND);
dialog.dismiss();
//If you are setting a dialog activity, create a style in styles.xml:
<style name="MyTheme" parent="@style/Theme.AppCompat.Light.Dialog">
<item name="windowActionBar">false</item>
<item name="windowNoTitle">true</item>
<item name="android:backgroundDimEnabled">false</item>
</style>
And in your Manifest, set the theme:
<activity android:name=".view.POSSelectCustomerDialogActivity"
android:theme="@style/MyTheme"
android:windowSoftInputMode="stateAlwaysHidden|adjustResize"/>