Immediate update to JCombobox in Java

Question

A person wishes to add a NEW Job to the database. A Combobox list the existing employers already in the database for the new Job to be added against. But if an employer is not present customers have the option click on a button to add an employer. Once added that employer should immediately be displayed in the textfield.

I am trying to achieve the above scenario with my coding and mysql database, but cant think of the logic to do so...

Table Employer

CREATE TABLE "Employer" ("employerID" INTEGER PRIMARY KEY  NOT NULL ,
"name" CHAR,
"industry" CHAR,
"contact1" CHAR,
"contact2" CHAR,
"email" CHAR,
"website" CHAR,
"facts" CHAR,
"phone" VACHAR)

Table Job

CREATE TABLE "Job" ("jobID" INTEGER PRIMARY KEY  NOT NULL ,
"employerID" INTEGER,
"title" CHAR,
"description" CHAR,
"type" CHAR,"salary" CHAR,
"benefits" CHAR,
"vacancies" INTEGER,
"closing" CHAR,
"requirement" CHAR,
"placement" BOOL,
"applyTo" CHAR,
"status" CHAR,
"posted" CHAR, 
"location" CHAR)

Class Employer_GUI - Consist of a simple form and save button which saves new EMPLOYERS into Employer table

private void SaveEmpButtonActionPerformed(java.awt.event.ActionEvent evt) {

    try {
        String sql = "INSERT INTO Employer (name,industry,contact1,contact2,email,website,facts,phone) VALUES (?,?,?,?,?,?,?,?)";
        pst = conn.prepareStatement(sql);

                    pst.setString(1, txtName.getText());
                    pst.setString(2, txtInd.getText());
                    pst.setString(3, txtC1.getText());
                    pst.setString(4, txtC2.getText());
                    pst.setString(5, txtEmail.getText());
                    pst.setString(6, txtWeb.getText());
                    pst.setString(7, txtFacts.getText());
                    pst.setString(8, txtPhone.getText());
                    pst.execute();
        JOptionPane.showMessageDialog(null, ""+txtName.getText()+" added to database!");
        this.setVisible(false);
    }

    catch (Exception e) {
            JOptionPane.showMessageDialog(null, ""+txtName.getText()+" could not be added!");
    }
    finally {
       try {
        rs.close(); pst.close();  }
         catch(Exception e) { } }  

}

//Class Job_GUI - Consist of a FORM to add JOBS only to Job table

private void fillCombo() {
    try {
        String sql = "SELECT * FROM Employer";
        pst = conn.prepareStatement(sql);
        rs = pst.executeQuery();

        while(rs.next()) {
            String empName = rs.getString("name");
            comboEmployer.addItem(empName);

        }
    }

How could the JComboBox comboEmployer be immediately have the selected item as the new Employer name just added?

Answer 1

If I understood you want the new employee that was added to be what is selected in the combobox?

Once you have got the new employees name and added it to combobox, simply call JComboBox#setSelectedItem(Object o) with the name of the new employee.

i.e:

String newEmpName=...;
//code to add new employee goes here
//code to fill combobox with update values goes here
//now we set the selecteditem of the combobox
comboEmployer.setSelectedItem(newEmpName);

UPDATE

As per your comments:

The basics:

1) Get new employee name or whatever identifier matches that of the items in your combobox from your add employee dialog.

2) Than simply call setSelectedItem(name) after the data has been added tocombobox`.

So you might see your Add Employer dialog return a name or have a method to get the name which was added to the database. In your combobox class after dialog is closed, you would refresh the combobox with new entries, get the name added via the add employee dialog and call JComboBox#setSelectedItem(..) with the name we got from Add employer dialog using getters or static variable

i.e:

class SomeClass {

    JFrame f=...;
    JComboBox cb=new ...;

    ...

    public void someMethod() {
       AddEmployerDialog addEmpDialog=new AddEmployerDialog(f);//wont return until exited or new name added

       String nameAdded=addEmpDialog.getRecentName();//get the name that was added

      //clear combobox of all old entries
      DefaultComboBoxModel theModel = (DefaultComboBoxModel)cb.getModel();
      theModel.removeAllElements();

       //refresh combobox with the latest names from db
       fillCombo();

       //now we set the selected item of combobox with the new name that was added
       cb.setSelectedItem(nameAdded);
  }

}

class AddEmployerDialog {

    private JDialog dialog;
    private String empName;//emp name will be assigned when save is pressed or whatever

    public AddEmployerDialog(JFrame frame) {

        dialog=new JDialog(f);
        dialog.setDefaultCloseOperation(JDialog.DISPOSE_ON_CLOSE);
        dialog.setModal(true);//so that we dont return control until exited or done
        //add components etc
        dialog.pack();
        dialog.setVisible(true);

    }

    public String getRecentName() {
        return empName;
    }

}