How to use populated jcombobox for selecting another jcombobox values?

[md nayeem]

i have 3 j combobox for  Depertment,Semester and Books.I populate the  Semester Jcombobox by Depertment jcombobox.now i want to  use Semester jCombobox to populate the Books Jcombobox.Need some Example.
my codes are here:

/*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */


import java.sql.Connection;
import java.sql.*;
import javax.swing.JOptionPane;

/**
 *
 * @author gsl
 */
public class Employee extends javax.swing.JInternalFrame {

    
    String gender="";
    int id;
    
  String[] dep={"Select Depaartment","Computer","Civil","Electrical","Telecom"};
    String[] Computer={"FirststSemester","SecondndSemester","ThirdrdSemester","FourthSemester","FifthSemester","SixthSemester","SeventhSemester"};
    String[] Civil={"FirststSemester","SecondndSemester","ThirdrdSemester","FourthSemester","FifthSemester","SixthSemester","SeventhSemester"};
    String[] Electrical={"FirststSemester","SecondndSemester","ThirdrdSemester","FourthSemester","FifthSemester","SixthSemester","SeventhSemester"};
    String[] Telecom={"FirststSemester","SecondndSemester","ThirdrdSemester","FourthSemester","FifthSemester","SixthSemester","SeventhSemester"};
    
    
  String[] books={"Select Books", "FirststSemesterBooks","SecondSemesterBooks","ThirdSemesterBooks","FourthSemesterBooks","FifthSemesterBooks","SixthSemesterBooks","SeventhSemesterBooks"}; 
  
    
   
    
    
   //driver under class  
    
    static final String JDBC_Driver="con.mysql.jdbc.Driver";
    static final String Db_URL="jdbc:mysql://localhost/employee_sys";
    
    static final String User="root";
    static final String pass= "";
   
public static Connection myconnection=null; 
public static Statement dstatement=null;


    
    public Employee() {
           try {
         //Registaring Driver
         Class.forName("com.mysql.jdbc.Driver");
         // Open Connection
         myconnection=DriverManager.getConnection(Db_URL, User, pass);
         dstatement = myconnection.createStatement();
         
       }
               
 catch(Exception ex){
     
     System.out.println(ex.getMessage());
    
 
 
 }      
        initComponents();
        
        
        
  //under in components
   
       
   cmbDep.removeAllItems();

        for (int i = 0; i < dep.length; i++) {
             cmbDep.addItem(dep[i]);
        }
  
  
  

        
 
        
 
        
        
        
   
        
        
        
        
        
        
        
    }

    /**
     * This method is called from within the constructor to initialize the form.
     * WARNING: Do NOT modify this code. The content of this method is always
     * regenerated by the Form Editor.
     */
    @SuppressWarnings("unchecked")
    // <editor-fold defaultstate="collapsed" desc="Generated Code">                          
    private void initComponents() {

        jPanel1 = new javax.swing.JPanel();
        jLabel1 = new javax.swing.JLabel();
        jLabel2 = new javax.swing.JLabel();
        jLabel3 = new javax.swing.JLabel();
        jLabel4 = new javax.swing.JLabel();
        txtName = new javax.swing.JTextField();
        txtAdrs = new javax.swing.JTextField();
        txtPhone = new javax.swing.JTextField();
        txtSalary = new javax.swing.JTextField();
        jLabel5 = new javax.swing.JLabel();
        cmbDep = new javax.swing.JComboBox<>();
        jLabel6 = new javax.swing.JLabel();
        cmbSems = new javax.swing.JComboBox<>();
        jLabel7 = new javax.swing.JLabel();
        cmbPos = new javax.swing.JComboBox<>();
        jLabel8 = new javax.swing.JLabel();
        btnMale = new javax.swing.JRadioButton();
        btnFemale = new javax.swing.JRadioButton();
        jPanel2 = new javax.swing.JPanel();
        btnSave = new javax.swing.JButton();
        btnSearch = new javax.swing.JButton();
        btnUpdate = new javax.swing.JButton();

        setClosable(true);
        setIconifiable(true);
        setMaximizable(true);

        jPanel1.setBackground(new java.awt.Color(102, 102, 255));
        jPanel1.setBorder(javax.swing.BorderFactory.createTitledBorder("EmployeeInfo"));

        jLabel1.setText("Name");

        jLabel2.setText("Address");

        jLabel3.setText("Phone");

        jLabel4.setText("Salary");

        jLabel5.setText("Depertment");

        cmbDep.setModel(new javax.swing.DefaultComboBoxModel<>(new String[] { "Item 1", "Item 2", "Item 3", "Item 4" }));
        cmbDep.addItemListener(new java.awt.event.ItemListener() {
            public void itemStateChanged(java.awt.event.ItemEvent evt) {
                cmbDepItemStateChanged(evt);
            }
        });

        jLabel6.setText("Semester");

        cmbSems.setModel(new javax.swing.DefaultComboBoxModel<>(new String[] { "Item 1", "Item 2", "Item 3", "Item 4" }));

        jLabel7.setText("Books");

        cmbPos.setModel(new javax.swing.DefaultComboBoxModel<>(new String[] { "Item1", "Item2", "Item3", "Item4" }));

        jLabel8.setText("Gender");

        btnMale.setText("Male");
        btnMale.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                btnMaleActionPerformed(evt);
            }
        });

        btnFemale.setText("Female");
        btnFemale.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                btnFemaleActionPerformed(evt);
            }
        });

        javax.swing.GroupLayout jPanel1Layout = new javax.swing.GroupLayout(jPanel1);
        jPanel1.setLayout(jPanel1Layout);
        jPanel1Layout.setHorizontalGroup(
            jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(jPanel1Layout.createSequentialGroup()
                .addGap(128, 128, 128)
                .addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                    .addComponent(jLabel2)
                    .addComponent(jLabel1)
                    .addComponent(jLabel3)
                    .addGroup(jPanel1Layout.createSequentialGroup()
                        .addGap(1, 1, 1)
                        .addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                            .addComponent(jLabel6)
                            .addComponent(jLabel5)
                            .addComponent(jLabel7)
                            .addComponent(jLabel8)
                            .addComponent(jLabel4))))
                .addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                    .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, jPanel1Layout.createSequentialGroup()
                        .addGap(38, 38, 38)
                        .addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                            .addComponent(txtSalary, javax.swing.GroupLayout.Alignment.TRAILING, javax.swing.GroupLayout.PREFERRED_SIZE, 245, javax.swing.GroupLayout.PREFERRED_SIZE)
                            .addComponent(txtPhone, javax.swing.GroupLayout.Alignment.TRAILING, javax.swing.GroupLayout.PREFERRED_SIZE, 244, javax.swing.GroupLayout.PREFERRED_SIZE)))
                    .addGroup(jPanel1Layout.createSequentialGroup()
                        .addGap(41, 41, 41)
                        .addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)
                            .addGroup(jPanel1Layout.createSequentialGroup()
                                .addComponent(btnMale, javax.swing.GroupLayout.PREFERRED_SIZE, 123, javax.swing.GroupLayout.PREFERRED_SIZE)
                                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                                .addComponent(btnFemale, javax.swing.GroupLayout.DEFAULT_SIZE, 119, Short.MAX_VALUE))
                            .addComponent(cmbDep, 0, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                            .addComponent(cmbSems, 0, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                            .addComponent(cmbPos, 0, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                            .addComponent(txtAdrs)
                            .addComponent(txtName))))
                .addContainerGap(75, Short.MAX_VALUE))
        );
        jPanel1Layout.setVerticalGroup(
            jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(jPanel1Layout.createSequentialGroup()
                .addGap(33, 33, 33)
                .addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                    .addComponent(jLabel1)
                    .addComponent(txtName, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
                .addGap(18, 18, 18)
                .addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                    .addComponent(jLabel2)
                    .addComponent(txtAdrs, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
                .addGap(27, 27, 27)
                .addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                    .addComponent(jLabel3)
                    .addComponent(txtPhone, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
                .addGap(37, 37, 37)
                .addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING)
                    .addComponent(jLabel4)
                    .addComponent(txtSalary, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
                .addGap(27, 27, 27)
                .addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                    .addComponent(jLabel5)
                    .addComponent(cmbDep, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
                .addGap(30, 30, 30)
                .addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                    .addComponent(jLabel6)
                    .addComponent(cmbSems, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
                .addGap(23, 23, 23)
                .addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                    .addComponent(jLabel7)
                    .addComponent(cmbPos, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
                .addGap(26, 26, 26)
                .addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING)
                    .addComponent(jLabel8)
                    .addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                        .addComponent(btnMale)
                        .addComponent(btnFemale)))
                .addContainerGap(15, Short.MAX_VALUE))
        );

        jPanel2.setBackground(new java.awt.Color(255, 255, 102));

        btnSave.setText("save");
        btnSave.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                btnSaveActionPerformed(evt);
            }
        });

        btnSearch.setText("search");
        btnSearch.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                btnSearchActionPerformed(evt);
            }
        });

        btnUpdate.setText("update");
        btnUpdate.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                btnUpdateActionPerformed(evt);
            }
        });

        javax.swing.GroupLayout jPanel2Layout = new javax.swing.GroupLayout(jPanel2);
        jPanel2.setLayout(jPanel2Layout);
        jPanel2Layout.setHorizontalGroup(
            jPanel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(jPanel2Layout.createSequentialGroup()
                .addGap(94, 94, 94)
                .addComponent(btnSave)
                .addGap(38, 38, 38)
                .addComponent(btnSearch)
                .addGap(34, 34, 34)
                .addComponent(btnUpdate)
                .addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
        );
        jPanel2Layout.setVerticalGroup(
            jPanel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(jPanel2Layout.createSequentialGroup()
                .addContainerGap()
                .addGroup(jPanel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                    .addComponent(btnSave)
                    .addComponent(btnSearch)
                    .addComponent(btnUpdate))
                .addContainerGap(24, Short.MAX_VALUE))
        );

        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addComponent(jPanel1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
            .addComponent(jPanel2, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addComponent(jPanel1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                .addComponent(jPanel2, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addContainerGap())
        );

        pack();
    }// </editor-fold>                        

    private void btnSaveActionPerformed(java.awt.event.ActionEvent evt) {                                        
        // TODO add your handling code here:
        
   try{
       
       String  name=txtName.getText();
       String  add=txtAdrs.getText();
       String  phone=txtPhone.getText();
       double  salary=Double.parseDouble(txtSalary.getText());
       String  dis=cmbDep.getSelectedItem().toString();
       String  city=cmbSems.getSelectedItem().toString();
       String  pos=cmbPos.getSelectedItem().toString();
        
               
               
       String sql="insert into  employee(name,address,phone,salary,district,city,position,gender) values ('"+name+"','"+add+"','"+phone+"',"+ salary+",'"+dis+"','"+city+"','"+pos+"','"+gender+"')";
             dstatement.executeUpdate(sql);
             
             JOptionPane.showMessageDialog (null,"Added Successful!");
         } catch (SQLException ex) {
             JOptionPane.showMessageDialog (null,ex.getMessage()+ "Added Failed!");
             
         }      
        

        
    }                                       

    private void btnMaleActionPerformed(java.awt.event.ActionEvent evt) {                                        
        // TODO add your handling code here:
        btnFemale.setSelected(false);
        gender="Male";  
    }                                       

    private void btnFemaleActionPerformed(java.awt.event.ActionEvent evt) {                                          
        // TODO add your handling code here:
        btnMale.setSelected(false);
        gender="Female";
    }                                         

    private void cmbDepItemStateChanged(java.awt.event.ItemEvent evt) {                                        
        // TODO add your handling code here:
          cmbSems.removeAllItems();
        
        if(cmbDep.getSelectedIndex() !=0)
        {
            String[] c;
            
            if (cmbDep.getSelectedIndex()==1)
            {
                c=Computer;
            }
            else if(cmbDep.getSelectedIndex()==2)
            {
                c =Civil;
            }
            else if(cmbDep.getSelectedIndex()==3)
            {
                c=Electrical;
            }
           
            
            else 
            {
                c=Telecom;
            }
            
            for(int i=0; i<c.length; i++)
            {
                cmbSems.addItem(c[i]);
            }
            
            
     
            
            
            
            
          }
   
   
        
        
    }                                       

    private void btnSearchActionPerformed(java.awt.event.ActionEvent evt) {                                          
        // TODO add your handling code here:
        try{
        
        String name=txtName.getText();
        String sql="select* from  employee where name='"+name+"'";
        ResultSet rs=dstatement.executeQuery(sql);
        
        rs.first();
        id=rs.getInt("id");
        String sname=rs.getString("name");
        String saddress=rs.getString("address");
        String sphone=rs.getString("phone");
        double ssalary=rs.getDouble("salary");
        String sdistrict=rs.getString("district");
        String scity=rs.getString("city");
        String sposition =rs.getString("position");
        String sgender=rs.getString("gender");
        
        txtName.setText(sname+"");
        txtAdrs.setText(saddress+"");
        txtPhone.setText(sphone+"");
        txtSalary.setText(ssalary+"");
       cmbDep.setSelectedItem(sdistrict+"");
       cmbSems.setSelectedItem(scity+"");
       cmbPos.setSelectedItem(sposition+"");
       
       if (sgender.equals("Female")){
            btnMale.setSelected(false);
            btnFemale.setSelected(true);
        } else {
            btnFemale.setSelected(false);
            btnMale.setSelected(true);
        }
       
 
      JOptionPane.showMessageDialog(null,"Data Found");
        
      }catch(SQLException ex){
      
      
     JOptionPane.showMessageDialog(null,"Data Not Found"+ex.getMessage());
      
      }

    }                                         

    private void btnUpdateActionPerformed(java.awt.event.ActionEvent evt) {                                          
        // TODO add your handling code here:
        
     try{
       
       String  name=txtName.getText();
       String  add=txtAdrs.getText();
       String  phone=txtPhone.getText();
       double  salary=Double.parseDouble(txtSalary.getText());
       String  dis=cmbDep.getSelectedItem().toString();
       String  city=cmbSems.getSelectedItem().toString();
       String  pos=cmbPos.getSelectedItem().toString();
        
       
       String sqlupdate="update   employee set name='"+name+"',address='"+add+"',phone='"+phone+"',salary="+salary+", district='"+ dis+"',city='"+city+"',position='"+pos+"',gender='"+gender+"' where id ="+ id;
             dstatement.executeUpdate(sqlupdate);
             
             JOptionPane.showMessageDialog(null, "Updated Successfully");
         } catch (SQLException ex) {
         JOptionPane.showMessageDialog(null, "Updated Failed!"+"/n"+ex.getMessage());    
             
         }    

    }                                         


    // Variables declaration - do not modify                     
    private javax.swing.JRadioButton btnFemale;
    private javax.swing.JRadioButton btnMale;
    private javax.swing.JButton btnSave;
    private javax.swing.JButton btnSearch;
    private javax.swing.JButton btnUpdate;
    private javax.swing.JComboBox<String> cmbDep;
    private javax.swing.JComboBox<String> cmbPos;
    private javax.swing.JComboBox<String> cmbSems;
    private javax.swing.JLabel jLabel1;
    private javax.swing.JLabel jLabel2;
    private javax.swing.JLabel jLabel3;
    private javax.swing.JLabel jLabel4;
    private javax.swing.JLabel jLabel5;
    private javax.swing.JLabel jLabel6;
    private javax.swing.JLabel jLabel7;
    private javax.swing.JLabel jLabel8;
    private javax.swing.JPanel jPanel1;
    private javax.swing.JPanel jPanel2;
    private javax.swing.JTextField txtAdrs;
    private javax.swing.JTextField txtName;
    private javax.swing.JTextField txtPhone;
    private javax.swing.JTextField txtSalary;
    // End of variables declaration                   
}

[Rob Camick]

What is the point of this question?

You were given a working example in your last question on this topic:

https://coderanch.com/t/672751/java/Loading-Values-JComboBox-depending-selection