Getting a warning for using throws key word on my function header

this is a method where i am throwing an exception called "Data Exception",so i have to add "throws DataException" to the function header right?But when I add it, i get a warning(From IDE) saying that -"com.DataException is never thrown in the method",but i am clearly throwing the DataException right(in 2 places)?Want to know what mistake i am doing here.Any help appreciated.

public ResponseEntity<?> uploadExcelFile( @RequestParam( "file" ) final MultipartFile file ) throws DataException       //Getting the warning to remove here.
    {
        try
        {
            if( NullEmptyUtils.isNull(file) || file.isEmpty() )
            {
                throw new DataException(StringConstants.EXCEPTION, StringConstants.FILE_IS_NULL_OR_EMPTY,
                        HttpStatus.BAD_REQUEST);
            }

            if( ExcelHelper.hasExcelFormat(file) )
            {
                excelService.save(file, getLoggedInUser());
            }
            else
            {
                throw new DataException(StringConstants.EXCEPTION, StringConstants.FILE_IS_NOT_AN_EXCEL_FORMAT,
                        HttpStatus.BAD_REQUEST);
            }

        }
        catch( DataException e )
        {
            logger.error(StringConstants.EXCEPTION, e);
            return buildError(new DataException("error", "Error occurred while uploading file",
                    HttpStatus.INTERNAL_SERVER_ERROR));
        }

        return buildResponse("Uploaded file ->" + file.getOriginalFilename());
    }

}

The throws clause is for exceptions that might get thrown while your method is running, but aren't explicitly caught within your method. In your case, you're certainly throwing a DataException, but then you have a catch (DataException e), which catches the exception. So the exception is never thrown out of the method, which means that you don't have to declare it.

You only have to declare an exception in a throws clause if it's

• thrown within the method (or in something called by the method)
• not caught within the method
• not a subtype of RuntimeException.

and you should avoid declaring any exceptions that don't meet these criteria. That's what the compile warning is telling you.

Remember the catch or declare rule for checked Exceptions, which says that :

• If code in your method is throwing an exception, then either
  • catch the exception in your method in by surrounding the code which is expected to throw an exception, by try-catch block OR
  • declare the exception in your method signature by using throws clause, so that caller of your method knows that your method can throw this exception and can handle.

In your case, as you are already catching exception in your method, you don't need to add in a throws clause.