Question

I am a novice in Java World. How to avoid confusion over variable declaration in MVC pattern over same variable?

For Example,

In Servlet (Controller):

String firstName     = request.getParameter("firstname");
String lastName      = request.getParameter("lastname");

In Bean (Model):

private String firstname;
private String lastname;

public Person(String FirstName, String LastName) {
    setFirstName(FirstName);
    setLastName(LastName);
}

//Getter and Setter Methods
public String getFirstName() {
  return firstname;
}
public void setFirstName(String FirstName) {
  this.firstname = FirstName;
}
public String getLastName() {
  return lastname;
}
public void setLastName(String LastName) {
  this.lastname = LastName;
}

In DAO (Data Access Layer):

public void savePerson(String firstName, String lastName) {
    // Method statements
}

And in JSP (View):

${person.firstname} ${person.lastname}

My Questions/Confusion?

1. What is the proper way of declaring same variable in different
   modules(controller,models,views,dao)? And how should I avoid confusion?

2. Is there any conventions I have to follow while declaring variables in different
   modules?

3. Should variables in Servlets and DAO be same? Should variables in Models/Bean
   be different from Servlet and DAO?

Answer 1

In your servlet these would be method variables. That’s pretty fine.

In your Model this works as a Model’s properties. That’s pretty fine, too.

In view you are actually referring to Model’s properties, and not declaring any variable, whatsoever.

In DAO, you are actually, persisting your Model.

So, In Servlet/Controller this will be something more like this,

Person p = new Person();
p.setFirstName(request.getParameter("firstname"));
p.setLastName(request.getParameter("lastname"));

And in your DAO, it would be more like this,

public void savePerson(Person person) {
    // Method statements
}

Hence, declaration only happens in Model. I hope it clears your confusion.