基于JCombobox Java上的selectedItem的JFrame

Question

I just started to develop in Java, so I have a newbie question, I have a Jcombobx that's getting filled from my database using this function:

private void fill(){
   try{
       con = DriverManager.getConnection("jdbc:....");
       Statement pst = con.createStatement();
       String sql = "select * from student";
       ResultSet rs = pst.executeQuery(sql);
       while(rs.next()){
            jCombo.addItem(rs.getString("strudent_name");
       }
   } catch (Exception e){
      System.out.println(e.getMessage);
 }

The code is working and the combo is filled from my database, the next step is to fill another JFrame from my database based on the selectedItem in the combobox, when I was developping in PHP I know that was easier because I only had to put the id in the select value and the name in the displayed. In android I could send in via Intent but I don't know how to do in jaa, because the next JFrame that must be opened has to get the details about the selected student, using informations from the other tables. Thanks for helping.

Answer 1

First create a wrapper class for student

public class Student
{

    private int id;
    private String name;
    //more fields here like grades, subjects etc

    public Student(int id, String name)
    {
        super();
        this.id = id;
        this.name = name;
    }



    public int getId()
    {
        return this.id;
    }



    public void setId(int id)
    {
        this.id = id;
    }



    public String getName()
    {
        return this.name;
    }



    public void setName(String name)
    {
        this.name = name;
    }



    @Override
    public String toString()
    {
        return name;
    }


}

Then you declare JComboBox like this

JComboBox<Student> jCombo = new JComboBox<>();

And then

private void fill(){
   try{
       con = DriverManager.getConnection("jdbc:....");
       Statement pst = con.createStatement();
       String sql = "select * from student";
       ResultSet rs = pst.executeQuery(sql);
       while(rs.next()){
        Student student = new Student(rs.getInt("student_id") , rs.getString("student_name"));     
         jCombo.addItem(student);
       } // while end

   } catch (Exception e){
      System.out.println(e.getMessage);
 }

When some button is clicked you can get id of selected student by

showDetailsButton.addActionListener(new ActionListener() {

        @Override
        public void actionPerformed(ActionEvent arg0)
        {
            Student selectedStudent = (Student) jCombo.getSelectedItem();
            new StudentDetails(selectedStudent.getId());

        }
    });

Where StudentDetails is a another JFrame

class StudentDetails extends JFrame 
{
    public StudentDetails(int studentID)
    {
        // "Select * from student where student_id =" + studentID;
        super();
        add(new JLabel("Detail of student with id " + studentID + " goes here"));
        setVisible(true);
        setSize(100, 100);

    }
}