用Java做个单线聊天室，为什么总是接收不到对方发出的消息。跪求高手指点
服务器端：
package HomeWork;
import javax.swing.*;
import javax.swing.border.Border;
import javax.swing.border.LineBorder;
import javax.swing.border.TitledBorder;
import java.awt.*;
import java.awt.event.*;
import java.io.BufferedReader;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.Date;
public class singlechat extends JFrame {
JTextArea textarea,textarea1;
//JTextField textfield;
JButton button,button1,button2,button3,button4,button5;
JPanel panel1 = new JPanel();
JPanel panel2 = new JPanel();
JPanel panel3 = new JPanel();
JPanel panel4 = new JPanel();
JScrollPane scrollpane;
public DataInputStream din;
public DataOutputStream dout;
public Socket socket ;
public static void main(String[] args) {
new singlechat();
}
public singlechat() {
super("聊天室");
addWindowListener(new WindowAdapter() {
public void windowClosing(WindowEvent e) {
try{
din.close();
dout.close();
socket.close();
System.exit(0);
}
catch (IOException ex){
System.out.println("client closing: "+ ex.toString());
}
}
});
//this.setLayout();
Font largeFont = new Font("TimesRoman", Font.BOLD, 20);
Border lineBorder = new LineBorder(Color.BLACK, 2);
button = new JButton("发送");
button1 = new JButton("老大");
button2 = new JButton("老二");
button3 = new JButton("老三");
button4 = new JButton("老四");
button5 = new JButton("老五");
textarea = new JTextArea(6, 30);
textarea1 = new JTextArea(3,30);
textarea.setForeground(Color.blue);
textarea.setFont(largeFont);
textarea.setBorder(lineBorder);
textarea1.setForeground(Color.red);
textarea1.setFont(largeFont);
textarea1.setBorder(lineBorder);
textarea1.setBackground(Color.cyan );
scrollpane = new JScrollPane(textarea);
//scrollpane.setPreferredSize(new Dimension(200, 200));
//textfield = new JTextField(20);//textfield要先new出来
//textfield.setForeground(Color.red);
// setContentPane(panel1);
panel1.setPreferredSize(new Dimension(400, 300));
//panel1.setBackground(Color.white);
// panel1.setForeground(Color.blue);
panel1.setVisible(true);
panel1.setBorder(new TitledBorder("显示区域"));
panel1.setLayout(new BorderLayout());// 设置边界布局
panel1.add(scrollpane, BorderLayout.CENTER);
//this.add(panel1);
// setContentPane(panel2);
//panel2.setBackground(Color.white);
//panel2.setForeground(Color.blue);
panel2.setVisible(true);
panel2.setPreferredSize(new Dimension(400, 100));
panel2.setBorder(new TitledBorder("输入区域"));
panel2.setLayout(new GridLayout(2,1,10,10));// 设置边界布局
panel2.add(textarea1);
panel2.add(button);
//this.add(panel2,BorderLayout.SOUTH);
// setContentPane(panel3);
//panel3.setBackground(Color.red);
//panel3.setForeground(Color.blue);
panel3.setVisible(true);
panel3.setLayout(new BorderLayout());
panel3.setPreferredSize(new Dimension(400, 600));
panel3.setBorder(new TitledBorder("聊天区域"));
panel3.add(panel1,BorderLayout.CENTER);
panel3.add(panel2,BorderLayout.SOUTH);
panel4.setVisible(true);
panel4.setPreferredSize(new Dimension(200, 600));
panel4.setBorder(new TitledBorder("群成员"));
panel4.setLayout(new GridLayout(20,1,10,0));
panel4.add(button1);
panel4.add(button2);
panel4.add(button3);
panel4.add(button4);
panel4.add(button5);
this.setTitle("聊天室");
this.setVisible(true);
this.setResizable(false);
this.setBounds(100,100,600,600);//这个函数 设置 窗口大小 及 显示位置的
this.add(panel3,BorderLayout.WEST);
this.add(panel4,BorderLayout.EAST);
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
// button.addActionListener(new ButtonListener());
try {
ServerSocket serverSocket = new ServerSocket(8000);
textarea.append("Server started at " + new Date() +
"\n server port is "+serverSocket.getInetAddress().getHostAddress()+
":"+serverSocket.getLocalPort() + "\n");
// Listen for a connection request
Socket socket = serverSocket.accept();
System.out.println("a client connected!");
DataInputStream din = new DataInputStream(socket.getInputStream());
DataOutputStream dout = new DataOutputStream(socket.getOutputStream());
while (true) {
button.addActionListener(new ListenerClass());
String ss;
ss = din.readUTF();
textarea.append("\n" + ss + "\n" );
}
}
catch(IOException ex) {
System.err.println("server:"+ex);
}
}
private class ListenerClass implements ActionListener {
public void actionPerformed(ActionEvent e) {
try{
String s;
s = textarea1.getText().toString();
textarea.append("\n" + s + "\n");
dout.writeChars(s);
}
catch (Exception ex) {
System.err.println("textarea exception: "+ex);
}
}
}
}
[解决办法]
有没有错误信息?
[解决办法]
空指针有对象为null引起的，你看看抛异常的那几行代码中有没有对象可能是null的
