android - How to resolve Attempt to invoke virtual method 'boolean java.lang.String.equalsIgnoreCase(java.lang.String)?

I have an app in which i am getting error "Attempt to invoke virtual method 'boolean java.lang.String.equalsIgnoreCase(java.lang.String)" please explain meaning and solution for that

code:-

 String receivedResult = parseJsonResultSetFav(result);
            if (receivedResult.equalsIgnoreCase("SUCCESS")) {
                CustomerTicketDialogClass ctdc = new CustomerTicketDialogClass(getActivity(),
                        "successful", "successfully sent mail to your email id ", "ViewDetails");
                ctdc.show();

                ctdc.setCanceledOnTouchOutside(false);
            } else {
                CustomerTicketDialogClass ctdc = new CustomerTicketDialogClass(getActivity(),
                        "failure", receivedResult, "ViewDetails");
                ctdc.show();
                ctdc.setCanceledOnTouchOutside(false);
            }