Why the getMethod for List<String> is not printing out the values in another Method?

[tangara]

I have been dealing with this problem for the longest time and I really hope someone can tell me what's happening and how to make the getMethod for List<String> returns the values.

public void insertTutor_Subject(int tutor_id, List<String> subjNames) throws MyDataException {
		
		Tutor m = new Tutor();
		System.out.println(tutor_id); //this will return the generated_id
		System.out.println(m.getSubjects());//not able to print out
try {
			//openConnection();		
			PreparedStatement ps3 = connection.prepareStatement("INSERT INTO project.tutor_subject(tutor_id, subjectName) VALUES (?, ?);");
			ps3.setInt(1, tutor_id);
			//System.out.println(m.getTutor_id()); //m.getTutor_id() will give you 0
			ps3.setObject(2, m.getSubjects());
			System.out.println(m.getSubjects());
			ps3.addBatch();
			ps3.setInt(1, tutor_id);
			ps3.setObject(2, m.getSubjects());
			ps3.addBatch();

At my controller :

String[] subj = request.getParameterValues("subject");
			List<String>subjs = new ArrayList<String>(Arrays.asList(subj));
		    m4.setSubjects(subjs); 
		    System.out.println(m4.getSubjects());	// able to see the values

My first question is m4.getSubjects at the controller is able to return the value so why is it not showing up at the insertTutor_Subject method?

My 2nd question is do I still need to OpenConnection(static method for JDBC Connection) in order for the insertion to work?

My last question is if the above - using Batch to insert the List<String> ? Is there anything wrong with this method ?

Thanks