Please have a look at this.

Question

There is something that happens in my code that I can't figure out. I have some varaibles defined in my main class, it's just one class anyway and the rest are inner anonymous. When I come to use them from an inner class, the code doesn't behave as I want it to unless I write the variables I'm using again inside the inner class, which is or are, actionListener/s.
here's the code to see what I'm talking about:
final String year = yearField.getText();
final String id = idField.getText();
final String student = studentIdField.getText();
final String section = sectionIdField.getText();
final String project = projectIdField.getText();
final String mark = markField.getText();
final String grade = gradeField.getText();
final String pass = passField.getText();
insert.addActionListener(new ActionListener()
    public void actionPerformed(ActionEvent e)
         String year = yearField.getText();
         String id = idField.getText();
         String student = studentIdField.getText();
         String mark = markField.getText();
         String section = sectionIdField.getText();
         String project = projectIdField.getText();
         String grade = gradeField.getText();
         String pass = passField.getText();
        if((year.equals(""))&&(id.equals(""))&&(student.equals(""))&&(mark.equals("")))
            JOptionPane.showMessageDialog(jf,
               "Please enter a value"
        else if(year.equals(""))
            JOptionPane.showMessageDialog(jf,
               "Please enter a value for Year"
        else if(id.equals(""))
            JOptionPane.showMessageDialog(jf,
                 "Please enter a value for ID"
        else if(student.equals(""))
             JOptionPane.showMessageDialog(jf,
               "Please enter a value for Student Id"
        else if(mark.equals(""))
             JOptionPane.showMessageDialog(jf,
                 "Please enter a value for Mark"
        else
              try
                      DriverManager.registerDriver(new com.microsoft.jdbc.sqlserver.SQLServerDriver());
     Connection connection = DriverManager.getConnection("jdbc:microsoft:sqlserver://localhost:1433","admin","admin");
     Statement statement = connection.createStatement();
     String query = "Insert into Results (Student_Id,Result_Year,Term,Degree,Pass,Project_Id,Univrs_Fac_Dept_Id,Grade,Univers_Fac_Dept_Section_Id) values ('"+student+"','"+year+"','"+term+"','"+mark+"','"+pass+"','"+project+"','"+department+"','"+grade+"','"+section+"')";
                     statement.executeUpdate(query);
     connection.close();
     catch(SQLException sqlerr)
          System.err.println(sqlerr);
     );Now, if I don't include the variables again inside the actionListener, the code doesn't move outside the if statement. Does anybody know why is that happening?
I just have another small question. When I need to check that a Chooser isn't empty, how do I do it? I mean with a string, you say: if(object.equals("")), what's for the items?
Thank you very much and sorry for the lot of talking.

Answer 1

you have to be careful with your variables:
the declared variables inside the actionlistener(s) are not these in your main class!!
what you might do:
a) let your main-class implement ActionListener
public class MainClass extends PARENTCLASS implements ActionListener {
   public static void actionPerformed(ActionEvent ae) {
}b) create your own event handler
public class MainClass extends PARENTCLASS {
   public MainClass() {
      insert.addActionListener(new YourActionListener(this));
public class YourActionListener extends ActionListener {
   private MainClass main;
   public YourActionListener(MainClass parent) {
      main = parent;
   public void actionPerformed(ActionEvent ae) {
      main.year = "abc";
      main.id = "id";
      // or implement setXXX methods -> main.setYear("abc"); main.setId("id"); ...
}hope it helps...