how to split numbers using substring

if (iscan.length() == 54)
               {
                   Toast.makeText(getApplicationContext(), "1", Toast.LENGTH_SHORT).show();
                   if (iscan.contains("(01)") && iscan.contains("(17)") && iscan.contains("(10)") && iscan.contains("(21)")) {
                       //String igtin = String.valueOf(iscan.indexOf(iscan, 4));
                       Toast.makeText(getApplicationContext(), "2", Toast.LENGTH_SHORT).show();
                       String igtin = iscan.substring(4, 18);
                       String iexpiry = iscan.substring(21, 27);
                       String ibatch = iscan.substring(31, 37);
                       String sSerialNo = iscan.substring(41, 54);
                       //String sGTINCode=iscan.substring(5,17);

                       gtin.setText(igtin);
                       expiry.setText(iexpiry);
                       batch.setText(ibatch);
                       serial.setText(sSerialNo);
                       duplicateSecondary(sSerialNo);

                   }
               }
                   else {
                       //Toast.makeText(getApplicationContext(), "Invalid Code", Toast.LENGTH_SHORT).show();
                       error.setText("Invalid Code is Scanned.. Please Scan a proper Bar Code");
                       error.setTextColor(Color.parseColor("#FFFFFF"));
                   }