How can i use the value which i got from a form as an variable in my dao class?

I am trying to create a page on which i will type the interest like java and then i will fetch all the rows from database which has interest as java so i have created this form element

<input class="form-control" type="text" placeholder="Search..." name="interest"><br>

This is my mapping in my controller

@ModelAttribute("courses")
	public Map<String, String> getCourseList() throws SQLException, IOException {

		return (new ServiceImpl()).getCourseList();
	}
	
	@RequestMapping(value="showCourses", method=RequestMethod.POST)
	public ModelAndView showCourses(@RequestParam("interest") String interest) {
		ModelAndView mv=new ModelAndView();
		mv.addObject("interest",interest);
		mv.setViewName("showCourses");
		return mv;
	}

I am fetching all the courses from the database but in my daoimpl class

public Map<String, String> courseList() throws SQLException, IOException {
		connect();
		Map<String, String> courseList = new HashMap<String, String>();
		String sql = "SELECT * from course;";
		resultSet = statement.executeQuery(sql);
		while (resultSet.next()) {
			courseList.put(resultSet.getString("CourseName"), resultSet.getString("CourseName"));
		}
		return courseList;
	}

in this courseList method i want to use the interest so that i can only fetch the courses which are of specific interest and show them on my jsp how can i use the interest in my daoImpl class?

Please have a look in below code snippet.

you have already implemented dao just need little modification on that method :-

public Map<String, String> getCourseList(String subjectInterest) {
	 connect();
     Map<String, String> courseList = new HashMap<String, String>();
     String sql = "SELECT * from course where subInterest = ?";
     statement.setString(1,subjectInterest);
     resultSet = statement.executeQuery(sql);
     while (resultSet.next()) {
        courseList.put(resultSet.getString("CourseName"), resultSet.getString("CourseName"));
     }
     return courseList;
}

Along with this you need to implement one service class from where you can call your dao method for fetching the course details like below :-

@Service
public class CourseService {
    @Autowired
    private CourseDAO courseDao;

    public Map<String, String> getCourseList(String subjectInterest) throws SQLException, IOException {
        return courseDao.getCourseList(subjectInterest);
    }
}

Post this in your controller need to change little bit something like below :-

@Controller
public class CourseController {

    @Autowired
    private CourseService courseService;

    @RequestMapping(value = "/showCourses", method = RequestMethod.POST)
    public String showCourses(@RequestParam("interest") String interest, Model model) throws SQLException, IOException {
	    model.addAttribute("interest", interest);
	    Map<String, String> courseList = courseService.getCourseList(interest);
	    model.addAttribute("courseList", courseList);
	    return "showCourses";
    }

}

And finally you need to loop courseList attribute in your showCourses.jsp, So you will be able to show courses based on interest.