写了个小程序，疏失查不出来

import java.awt.*;import java.awt.event.*;import java.io.*;import java.net.*;import java.util.*;public class ChatClient extends Frame {    TextField tf = new TextField();    TextArea ta = new TextArea();    Socket s = null;    DataOutputStream dos = null;    DataInputStream dis = null;    private boolean bool1 = false;    public static void main(String[] args) {        new ChatClient().launchFrame();    }    public void launchFrame() {        this.setSize(300, 300);        this.setLocation(400, 300);        this.add(ta, BorderLayout.NORTH);        this.add(tf, BorderLayout.SOUTH);        pack();        this.addWindowListener(new WindowAdapter() {            public void windowClosing(WindowEvent arg0) {                System.exit(0);            }        });// 匿名类，摁右上角关闭窗口功能；        tf.addActionListener(new TFListener());        this.setVisible(true);        connect();// 调用connect();        new Thread(new Get()).start();    }    public void connect() {        try {            s = new Socket("127.0.0.1", 8888);            System.out.println("I am connecting to the server...");            dos = new DataOutputStream(s.getOutputStream());            dis = new DataInputStream(s.getInputStream());            bool1 = true;        } catch (UnknownHostException e) {            e.printStackTrace();        } catch (IOException e) {            e.printStackTrace();        }    }        public void disconnect() {                try {            dos.close();            dis.close();            s.close();        } catch (IOException e) {            e.printStackTrace();        }    }        private class Get implements Runnable {                        public void run() {            try {                while(bool1) {                String str = dis.readUTF();                ta.setText(str);                }            } catch (IOException e) {                e.printStackTrace();            }        }            }    private class TFListener implements ActionListener {        public void actionPerformed(ActionEvent arg0) {            String str = tf.getText();            ta.setText(str);            tf.setText("");                        try {                dos.writeUTF(str);                dos.flush();            } catch (IOException e) {                e.printStackTrace();            }        }    }    }

import java.net.*;import java.io.*;import java.util.*;public class ChatServer {    List<Client>clients = new ArrayList<Client>();        public static void main(String[] args) {                new ChatServer().started();    }        public void started() {                boolean started1 = false;        ServerSocket ss = null;        Socket s = null;                try {            ss = new ServerSocket(8888);        } catch(BindException e) {            System.out.println("The port has been in used,try another...");            System.exit(0);        } catch(Exception e) {            e.printStackTrace();        }                try{            started1 = true;//建立连接后started1变为true；            while(started1) {                s = ss.accept();                Client c = new Client(s);System.out.println("A client is connecting to me...");                new Thread(c).start();                            }        } catch (IOException e) {            e.printStackTrace();        } finally {            try {                ss.close();            } catch (IOException e1) {                e1.printStackTrace();            }        }    }        public class Client implements Runnable {                private Socket s;        private DataInputStream dis;        private DataOutputStream dos;        private boolean started2 = false;                Client(Socket s) {            this.s = s;            started2 = true;            try {                dis = new DataInputStream(s.getInputStream());                dos = new DataOutputStream(s.getOutputStream());            } catch (IOException e) {                e.printStackTrace();            }        }            public void send(String str) {        try {            dos.writeUTF(str);            dos.flush();        } catch (IOException e) {            e.printStackTrace();        }    }    public void run() {                     try {            while(started2) {                String str;                str = dis.readUTF();System.out.println(str);                for(int i = 0; i < clients.size(); i++) {                    Client c = clients.get(i);                    c.send(str);                }                                /*for(Iterator<Client>it = clients.iterator(); it.hasNext();) {                    Client c = it.next();                    c.send(str);                }*/                                /*Iterator<Client>it = clients.iterator();                while(it.hasNext()) {                    Client c = it.next();                    c.send(str);                }*/                                    }                } catch (IOException e) {                    System.out.println("A client has been out...");                } finally {                    try {                        if(dis != null) dis.close();                        if(dos != null) dos.close();                        if(s != null) s.close();                    } catch (IOException e1) {                        e1.printStackTrace();                    }               }          }     }        }