- ``` package myclass; import myclass.*; import java.awt.*; import java.awt.event.*; import java.applet.*; import javax.swing.*; import java.net.*; import java.io.*; import java.util.*;
public class Server extends Thread{
ServerSocket serverSocket; //声明套接字
static Vector userOnLine = new Vector(0,1); //存储在线用户信息
static Vector chatGainedMessage = new Vector(0,1); //存储在线聊天信息与留言
static Vector userAdvice =new Vector(0,1);
public Server(){
chatGainedMessage.addElement("");
try{
serverSocket = new ServerSocket(1001);
}
catch(IOException e){
fail(e,"无法启动服务器!");
}
System.out.println("服务器启动.......");
this.start(); //启动server线程
}
public static void fail(Exception e,String str){
System.out.println(str + "." + e); //定义异常输出格式
}
public void run(){
try{
while(true){
Socket client = serverSocket.accept();
Connection connect=new Connection(client);
}
}
catch(IOException e){
fail(e,"Not listening");
}
}
//********************************server 的主函数****************************************
public static void main(String arg[]){
new Server(); //启动服务器
}
}
为什么提示
Exception in thread "Thread-0" java.lang.NullPointerException
at myclass.Server.run(Server.java:42)
是哪里重复创建了吗