Remove Default Background From custom Dialog also Dialog Activity

requestWindowFeature(Window.FEATURE_NO_TITLE);
getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
WindowManager.LayoutParams.FLAG_FULLSCREEN);
        getWindow().setBackgroundDrawable(
new ColorDrawable(android.graphics.Color.TRANSPARENT));

Note: wirte AboveCode in OnCreate if create Activity As Custom Dialog 


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LayoutInflater dailog = LayoutInflater.from(context);
 final View deleteDialogView = dailog.inflate( R.layout.dailog_popup(Your Xml Layout Name), null);
        Dialog alertdailog = new Dialog(context);
   alertdailog .requestWindowFeature(Window.FEATURE_NO_TITLE);
  alertdailog.getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);
    alertdailog.getWindow().setBackgroundDrawable(new ColorDrawable(android.graphics.Color.TRANSPARENT));
alertdailog.setContentView(your View Name);
alertdailog.setCanceledOnTouchOutside(true);

alertdailog.show();