请教一个Java的Swing监视器问题.

CSDN的大神们，经过了今天晚上的学习与代码实施，我初步将我的需求类进行了如下的修改：
    package c_port_packageBJTeacher;import java.awt.Dialog;
import java.awt.Rectangle;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.ItemEvent;
import java.awt.event.ItemListener;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import java.awt.event.WindowEvent;
import java.awt.event.WindowListener;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.OutputStream;
import java.net.InetAddress;import javax.swing.DefaultComboBoxModel;
import javax.swing.JComboBox;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.ScrollPaneConstants;
//创建ChatClient类作为聊天窗口；
public class Complete_ChatForeUITeacherClient0 extends AFrame implements WindowListener,KeyListener,ItemListener, ActionListener
{
CaptureScreen cjco = null;
int lennum = 0;
int MyVisiblestate = 1;
String SendInfo = "";
public String MyFriendIP = "";
String MyURLLocal = "";
private static final long serialVersionUID = 1L;
static Integer ChatPartnerSerialMark = 200;
Integer ChatFriNum = 200;
JScrollPane jspanel0 = null;
JScrollPane jspanel1 = null;
static DataOutputStream dops3 = null;
JPanel jp = new JPanel();
static DataInputStream dips3 = null;
boolean started = false;
InetAddress addr = null;
String title = "获取好友资料";
String chatword = null;
Dialog ordernum = new Dialog(this,title,started);
    String str;
    int T =0;
    public static String UIDLocal = null;
    static String roleLocal = null;
    static String iPAddressLocal = null;
    String Local_Teacher_facia = null;
    Integer MyIndex = -1;
    public String MyChatObjrolE = null;
    JPanel jp1 = new JPanel();
    public JTextArea Jta2 = new JTextArea();
String TeacherFuct = null;
public JTextArea Jta1 = new JTextArea();
String[] s = {"待选择","测试功能1","测试功能2","测试功能3","测试功能4","测试功能5","测试功能6","测试功能7","测试功能8","测试功能9","测试功能10","测试功能11","测试功能12","测试功能13"};
JComboBox<String> combo1 = null;
MyJButtonPayformyfuct jb1 = null;
OutputStream outputstream = null; //CaptureScreen capScreen = new CaptureScreen();

public Complete_ChatForeUITeacherClient0(String URL,Integer MyNum,String User_facia,Integer ChatObjectNum,String ChatObjrolE,String MyFriIP){
this.setTitle(User_facia);
System.out.println("C端Complete_ChatForeUITeacherClient");
this.setBounds(new Rectangle(419,92,590,550));
MyURLLocal = URL;
System.out.println("C端最关心数据，URL值能够走到C端的聊天界面的构造方法："+MyURLLocal);
MyIndex = MyNum;
roleLocal = "Teacher";
ChatPartnerSerialMark = ChatObjectNum;
System.out.println("CJ！！加油！！最牛逼伟望特必！！"+ChatObjectNum);
MyChatObjrolE = ChatObjrolE;
MyFriendIP = MyFriIP;
iPAddressLocal = GetMyLocalIP.catchLocalIP();
combo1 = new JComboBox<String>(s);
combo1.addItem("");

//TODO:
Jta2.addKeyListener(this);
combo1.addItemListener(this);
Jta1.setLineWrap(true); //如果加上这一句，那么水平方向的滚动条永远不会出现。
  Jta1.setEditable(false);
combo1.setBounds(new Rectangle(28,240,200,20));
    jspanel0=new JScrollPane(Jta1);
    jspanel1 = new JScrollPane(Jta2);
    jspanel0.setBounds (new Rectangle (10,10,500,220));
    jspanel1.setBounds (new Rectangle (10,280,500,220));
    jspanel0.setVerticalScrollBarPolicy(ScrollPaneConstants.VERTICAL_SCROLLBAR_AS_NEEDED);
    jspanel0.setHorizontalScrollBarPolicy(ScrollPaneConstants.HORIZONTAL_SCROLLBAR_NEVER);
    jspanel1.setHorizontalScrollBarPolicy(ScrollPaneConstants.HORIZONTAL_SCROLLBAR_NEVER);
jspanel1.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED);
jp1.setLayout(null);
Jta1.setLineWrap(true);//激活自动换行功能
Jta2.setLineWrap(true);
Jta2.setWrapStyleWord(true);//激活断行不断字功能
    Jta1.setWrapStyleWord(true);//激活断行不断字功能
jb1.setBounds(new Rectangle(321,240,150,20));
jb1.addActionListener(this);
jp1.setBounds(new Rectangle(10,10,590,550));
jp1.add(jb1);
jp1.add(combo1);
jp1.add(jspanel0);
  jp1.add(jspanel1);
  setVisible(true);
  this.addWindowListener(this);
}

public void start() {
this.add(jspanel0);
this.add(jspanel1);
this.add(jp1);
jp1.setVisible(true);
this.setVisible(true);
} @Override
public void windowActivated(WindowEvent e) {
// TODO Auto-generated method stub

} @Override
public void windowClosed(WindowEvent e) {
// TODO Auto-generated method stub SocketClient so2 = new SocketClient(Recv.D_PORT_SERVER,9911);
synchronized(so2){
    so2.writeStr("18丗18丗"+"Teacher"+"丗"+RelayNo1.LocalMyWorkNum+"丗"+"Teacher"+"丠"+RelayNo1.LocalMyWorkNum+"丠"+ChatPartnerSerialMark+"丠"+"Teacher"+"丠"+"BeiJing"+"丗"+"C"+"丗"+"BeiJing","Complete_ChatForeUITeacherClient");
    so2.getMyResourceBack();
}
} @Override
public void windowClosing(WindowEvent e) {
// TODO Auto-generated method stub
SocketClient so3 = new SocketClient(Recv.S_PORT_SERVER,8811);
String content = "8丗IcloseOneFrame丗C丗Teacher丗"+NoteUserLoginFrame.MyworkNum;
so3.writeStr(content, "Complete_ChatForeUITeacherClient");
so3.getMyResourceBack();
this.setVisible(false);
} @Override
public void windowDeactivated(WindowEvent e) {
// TODO Auto-generated method stub
} @Override
public void windowDeiconified(WindowEvent e) {
// TODO Auto-generated method stub

}

public static void main(String[] args){
new Complete_ChatForeUITeacherClient("www.baidu.com",0,"CJCO！！加油！！",2,"Teacher","222.196.1.8").start(); }
@Override
public void windowOpened(WindowEvent e)
{
// TODO Auto-generated method stub

}
@Override
public void windowIconified(WindowEvent e) {
// TODO Auto-generated method stub

}

public void changeTitle(String ficia){
this.setTitle(ficia);
} @Override
public void keyPressed(KeyEvent e) {
// TODO Auto-generated method stub
     if(e.isControlDown()&&e.getKeyCode()==KeyEvent.VK_ENTER){
String Chatword = RelayMyJButtonLogin.MyUID+" "+GetTheSysData.getTheLocalData()+" "+GetMySysTime.getNowTime()+"\r\n     "+Jta2.getText().trim();
SendInfo = Chatword.replaceAll("\r\n", "丱");
Jta1.append(Chatword+"\r\n");
Jta1.setCaretPosition(Jta1.getText().length());
Jta2.setCaretPosition(Jta2.getText().length());
Jta2.setText("");
sendInfo(SendInfo);
     } }

public void sendInfo(String Info){
Integer MySysserNum = Recv.MySystemserialnum;
    String str = "1丗"+MySysserNum+"丠"+"Teacher"+"丠"+ChatPartnerSerialMark+"丠"+MyChatObjrolE+"丠"+iPAddressLocal+"丠"+Info+"丗"+"C"+"丗"+"Teacher"+"丗"+MySysserNum; SocketClient so3 = new SocketClient(Recv.S_PORT_SERVER,8811);
synchronized(so3){
so3.writeStr(str,"Complete_ChatForeUITeacherClient");
}
String str0 = "1丗1丗"+"Teacher"+"丗"+MySysserNum+"丠"+"Teacher"+"丠"+ChatPartnerSerialMark+"丠"+MyChatObjrolE+"丠"+iPAddressLocal+"丠"+Info+"丠"+Recv.MyServerPlace+"丗"+"C"+"丗"+Recv.MyServerPlace;
SocketClient so2 = new SocketClient(Recv.D_PORT_SERVER,9911);
so2.writeStr(str0, "Complete_ChatForeUITeacherClient");
so2.getMyResourceBack();
System.out.println("C端通信报文"+str0);
} @Override
public void keyReleased(KeyEvent e) {
// TODO Auto-generated method stub

} @Override
public void keyTyped(KeyEvent e) {
// TODO Auto-generated method stub

} @Override
public void itemStateChanged(ItemEvent e) {
// TODO Auto-generated method stub
TeacherFuct = (String)combo1.getSelectedItem();
if(e.getStateChange() == ItemEvent.SELECTED)
             {
if(TeacherFuct.equals("测试功能1")){

new Code_Customer_OrderNum(MyChatObjrolE);
combo1.setSelectedIndex(0);
}else if(TeacherFuct.equals("测试功能2")){

String url = Recv.MyJButton0URL[ChatPartnerSerialMark];
System.out.println("C端最关心数据"+url);
BareBonesBrowserLaunch.openURL(url);
//
}else if(TeacherFuct.equals("测试功能3")){
combo1.setSelectedIndex(0);
if(cjco==null){
cjco = new CaptureScreen();
}else if(cjco.isVisible()){

}else{
cjco.setVisible(true);
}
//
}else if(TeacherFuct.equals("测试功能4")){
new ManageC_port_SendFriendFileFuct(Recv.MyFriIP);
//
}else if(TeacherFuct.equals("测试功能5")){
new ManageTheC_port_Recv_FriendFile(GetMyLocalIP.catchLocalIP());
//
}else if(TeacherFuct.equals("测试功能6")){
new CustomerCompliainUI();
//
}else if(TeacherFuct.equals("测试功能7")){
//TODO：添加本按钮的“测试功能7的类的执行方法”.
//
}else if(TeacherFuct.equals("测试功能8")){
//TODO：添加本按钮的“测试功能8的类的执行方法”.
//
}else if(TeacherFuct.equals("测试功能9")){
BareBonesBrowserLaunch.openURL(MyURLLocal);
//
}else if(TeacherFuct.equals("测试功能10")){
new ChatClientFriendlist(ManageC_port_MDSpara0Channel_Thread.Locallog);
//
}else if(TeacherFuct.equals("测试功能11")){
new SchemeMemory(ChatPartnerSerialMark,MyChatObjrolE);
//
}else if(TeacherFuct.equals("测试功能12")){
new PayForMyHyperRights(MyChatObjrolE);
initComboBox();
}else{
new SaveMyChatlogtoFile(MyChatObjrolE,ChatPartnerSerialMark,Recv.MyServerPlace);
}

}if(e.getStateChange() == ItemEvent.DESELECTED)
    {
combo1 = new JComboBox<String>(new DefaultComboBoxModel<String>());
combo1.addItem("value");
    }
}

public void initComboBox(){
String[] s = {"待选择","测试功能1","测试功能2","测试功能3","测试功能4","测试功能5","测试功能6","测试功能7","测试功能8","测试功能9","测试功能10","测试功能11","测试功能12","测试功能13"};
JComboBox<String> combo1 = new JComboBox<String>(s);
combo1.addItemListener(this);
} @Override
public void actionPerformed(ActionEvent e) {
// TODO Auto-generated method stub

}}
    但是，还是有一个问题没有解决：
    让我的用户在选择“测试功能n”的时候，能够弹出对应的“具体功能响应类”，在用户关闭具体功能后，能够进行：
    “用户再次打开上文同一个功能的时候”，我的JComboBox能够进行：
    “在我的JComboBox的实例还是原先的SelectedItem的值”的场景下，能够进行我的对应于“某一个测试功能n”的具体类型的调用.
    我的问题就是：
    在对我的JComboBox的实例进行监视的时候，怎样进行代码的书写，能够得到：
    在用户选中了一个选项之后，可以再次选择一个相同的选项，并且，调用这个选项所提供的功能？
    也就是：
    怎样能够改变JComboBox对象的SelectedItem的值.
    谢谢高手！！
现在还有做Swing开发的呀？
不过拿来学习还是可以的！
不是有JComboBox不是有setSelectedItem(Object anObject)方法吗，然后updateUI()刷新。

调试易

请教一个Java的Swing监视器问题.

解决方案 »