Open Internal Jframe after clicking button

Question

I have written this code EmployeeTable.java

package com.xyz.view.employeelist;

import java.awt.Font;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.ButtonGroup;
import javax.swing.JButton;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JRadioButton;
import javax.swing.JScrollPane;
import javax.swing.JTable;
import javax.swing.JTextField;
import javax.swing.table.DefaultTableModel;
import javax.swing.table.TableModel;
import com.xyz.view.iframe.employeedetail.EmployeeofficeDetail;

public class EmployeeTable extends JFrame
{
private JTextField Find;
private JLabel jFind,jDepartment,jDesignation,byName,bySalary;
private JButton SearchButton,add_Employee,getList,removeEmployee,save;
private JComboBox<String> Department, Designation;
private JTable EmpTable;
private JScrollPane  EmpTableScrollpane;
private JRadioButton sortByName,sortBySalary;
private ButtonGroup radioButton;
EmployeeofficeDetail e;

EmployeeTable()
{   

    setLayout(null);

    //------------ Text Feild ---------------------------
    jFind = new JLabel("Find :");
    jFind.setFont(new Font("Copperplate Gothic", Font.PLAIN, 16));
    jFind.setBounds(10, 20, 40, 20);

    Find = new JTextField(5);
    Find.setBounds(70, 20, 100, 20);

    //--------------------- Search Button -------------------------
    SearchButton = new JButton("Search");
    SearchButton.setBounds(190,20, 80, 20);

    //--------------------------- Get all list -------------------------

    getList = new JButton("Get All Employee List");
    getList.setBounds(160, 360, 200, 20);

    //---------------------- Add new Employee button -----------------

    add_Employee = new JButton("ADD Employee");
    add_Employee.setBounds(10, 400, 120, 20);

    //--------------------- Remove Employee Button --------------------

    removeEmployee = new JButton("Remove Employee");
    removeEmployee.setBounds(150, 400, 140, 20);

    //---------------------- Save Button -------------------------

    save = new JButton("Save");
    save.setBounds(310, 400, 100, 20);

    //------------------- Department Combobox ----------------------

    jDepartment = new JLabel("Department");
    jDepartment.setFont(new Font("Copperplate Gothic", Font.PLAIN, 16));
    jDepartment.setBounds(10, 50, 90, 30);
    String department[]={"Select Department","Software Development","Testing","Database","Financial","Planning","Human Resources"};
    Department = new JComboBox<String>(department);
    Department.setBounds(100, 50, 200, 30);

    //----------------- Designation Combobox -------------------------

    jDesignation = new JLabel("Designation");
    jDesignation.setBounds(10, 100,90, 20);
    jDesignation.setFont(new Font("Copperplate Gothic", Font.PLAIN, 16));
    String post[]={"Select Designation","Junior Developer","Senior Developer","Project Manager","Manager","Tester","Trainee"};
    Designation = new JComboBox<String>(post);
    Designation.setBounds(110, 100, 200, 30);

    //--------------------- Table -------------------------------

    Object[] column = {"ID","Name","salary","Designation","Department","Date of Joining"};
    Object[][] data = {{1,"amit"},{2,"raj"},{3,"ram"},{4,"rina"},{5,"sara"}};
    TableModel emp = new DefaultTableModel(data, column);
    EmpTable = new JTable(emp);
    EmpTableScrollpane = new JScrollPane(EmpTable);
    EmpTableScrollpane.setBounds(10, 140, 480, 200);

    //--------------------------- Radio Buttons -------------------------

    radioButton = new ButtonGroup();

    sortByName = new JRadioButton("Sort Table By Name");
    sortByName.setBounds(10, 430, 160, 20);

    sortBySalary = new JRadioButton("Sort Table By Salary");
    sortBySalary.setBounds(200, 430, 160, 20);


    add(jFind);
    add(Find);
    add(SearchButton);
    add(jDepartment);
    add(Department);
    add(jDesignation);
    add(Designation);
    add(EmpTableScrollpane);
    add(getList);
    add(add_Employee);
    add(removeEmployee);
    add(save);

    radioButton.add(sortByName);
    radioButton.add(sortBySalary);
    add(sortByName);
    add(sortBySalary);

    add_Employee.addActionListener(new ActionListener(){

        @Override
        public void actionPerformed(ActionEvent a) {
            if(a.getSource()==add_Employee)
            {
            e = new EmployeeofficeDetail();
                e.setTitle("Registration Form");
                e.setVisible(true);
            }       
        }
    });
} 
public static void main(String args[]) 
{
    JFrame f=new EmployeeTable();
    f.setVisible(true);;
    f.setSize(500, 500);
    f.setResizable(false);
    f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
}

And EmployeeOfficedetail.java

import javax.swing.JButton;
import javax.swing.JComboBox;
import javax.swing.JInternalFrame;
import javax.swing.JLabel;
import javax.swing.JTextField;

public class EmployeeofficeDetail extends JInternalFrame
{
private JTextField name;
private JLabel jName;
private JButton jSave,jNext;
private JComboBox<String> jDepartment;

public EmployeeofficeDetail()
{
    jName = new JLabel("Employee Name");

    name = new JTextField();

    jSave = new JButton();

    jDepartment = new JComboBox<String>();

    add(jName);
    add(name);
    add(jSave);
    add(jDepartment);
}
}

I want to open EmployeeOfficedetail frame on clicking add employee button so that emploeetable frame should be disappear but my code is not working. and also how to write actionlistener for combobox and radiobutton in my code so table value can be sorted accordingly.for example if i select radio button sort by name it will sort table according to name.