如何将信息从一个 class 传递到另一个

Question

I am creating a program which allows the user to input details of customers. When they have saved each customers record there is the choice to add additional information. I am having trouble getting the the name of the saved file in my append class. I need the filename so I can then save the additional information to the same file already created for the customer. How do I pass the file name from one file to another.

File FName = fileChooser.getSelectedFile();
      String name = FName.getName();

 public String getname() { return name; }

This code is in my customer class how do I get this information in my append class??

Answer 1

Possibly something like this:

Customer customer = new Customer();
// do some stuff with your customer object, including initiating the File and saving its name to a String field called name
Append append = new Append();
append.foo(customer.getName()); // passes the name of the file to the foo method of class Append

This assumes that you'll only want the name of the file in that one method (though you could save it to a field as part of method foo() ). You'd need to implement a method foo(String name) in class Append.

Another option would be to pass it as a constructor of Append:

Append append = new Append(customer.getName());
append.foo();

For this, you'd need to implement a constructor Append(String name) in class Append.

Answer 2

There are a couple of ways to do this depending on what exactly it is you are trying to do.

1. Give the Append class a member variable of the Customer class
2. Have the Append class constructor take a parameter that would refer to a Customer, such as a String of name or a Customer object as this is Java

Answer 3

Your question is not entirely clear to me, but here's a problems you might run into based on your description:

• What is getName() supposed to return, the name of the file, or the name of the person? If it's supposed to return the file name, then use getFileName() instead - it's clearer!

I don't really understand why you'd need an Append class. Personally, I'd handle appending additional info inside the Customer class. I'd do it so that every time a value is added or changed, the info is saved back into the file like:

class Customer {
    public void setForename(String forename) { 
        this.forename = forename;
        save();
    }
    public void setSurname(String surname) { 
        this.surname = surname;
        save();
    }
    public void save() {
        // clear file
        // add new content
        String fileContents = "forename="+forname+"&surname="+surname;
        // save to file
    }

Maybe I'm not understanding your needs correctly though...

Answer 4

In addition to DeadPassive's answer of associating the additional information with the Customer object:

The saving of the Customer data does not belong in the Customer Class. The logic of persisting the data belongs in a seperate layer than the code that deals with manipulating the problem domain. A controller or service class seems like a more appropriate place to put the persistance logic.