Unable to use combo box variable name for a different class

Question

I am trying to populate options for a combo box named cmb_course, the options will be pulled from my database in microsoft access, my problem is on the line below

cmb_course.addItem(rs.getString("courseName"));

cmb_course gets highlighted in red with the error

"cannot find symbol symbol: variable cmb_course location: class student"

my main file is the studentForm.java

the file where the combo box named cmb_course has been created is studentJframe.java

and finally I created another class which is the student.java where I am trying to build the function.

I have researched about using a getter and setter for this but I am fairly new to jframe and cannot fully grasp the concept that much because this was not yet explained to us by the professor yet it was given as part of our project

I hope someone can elaborate on this matter.

public class student {
      final String K_LIB = "jdbc:ucanaccess://";
      final   String K_DB_LOC = "C://";
      final  String K_DB_NAME = "students.accdb";
      String configuration = K_LIB + K_DB_LOC + K_DB_NAME;

public void fillComboBox(){

    try{
        Connection conn = DriverManager.getConnection(configuration);
         Statement s = conn.createStatement();
             ResultSet rs=s.executeQuery("Select courseName from course");
            while(rs.next()){
                cmb_course.addItem(rs.getString("courseName"));
            }
        }
    catch(Exception e){
        System.out.println(e.getMessage());
    }

}

}

that is true, there is no reference declared under the name ***cmb_course*** in that class.... — ΦXocę 웃 Пepeúpa ツ, Aug 23 '17 at 12:02
how is the compiler been able to guess what or where is **cmb_course** declared... — ΦXocę 웃 Пepeúpa ツ, Aug 23 '17 at 12:03
It doesn't know where to search for `cmb_course`, because you didn't tell it. Try, for example, adding parameter for `fillComboBox()` method where you will pass your JFrame. — M. Prokhorov, Aug 23 '17 at 12:05
[What does a “Cannot find symbol” compilation error mean?](https://stackoverflow.com/questions/25706216/what-does-a-cannot-find-symbol-compilation-error-mean) You should probably just read a Java textbook - you're missing some fundamental knowledge about how Java works that I don't think can really be covered in sufficient detail in an answer here. — Bernhard Barker, Aug 23 '17 at 12:23
Just declare your combo box(cmb_course) in class Student and it will magically work. — user3437460, Aug 23 '17 at 13:05

Tony Stark · Answer 1 · 2017-08-23T12:23:57.973

0

How would compiler will know cmb_combo variable is declared in StudentForm.java.

You can create a getter method in Student.java class which will resultset. Call the Student.java class getter method from StudentForm.java class and catch the returned value in a variable.

edited Aug 23 '17 at 12:23

answered Aug 23 '17 at 12:14

Tony Stark

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Unable to use combo box variable name for a different class

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