源代码如下：
GetUserInfo.java代码：
package testbeans;
import java.sql.*;
import java.util.*;
public class GetUserInfo {
public Connection con;
public GetUserInfo(){
try{
Class.forName( "sun.jdbc.odbc.JdbcOdbcDriver ");
String ulr= "jdbc:odbc:forum ";
String user= " ";
String pwd= " ";
con=DriverManager.getConnection(ulr,user,pwd);
} catch(Exception e)
{e.printStackTrace();
}
}
public Vector getInfo()
{ Vector result=new Vector();
String sql= "select * from topic ";
try{
Statement stmt=con.createStatement();
ResultSet rs=stmt.executeQuery(sql);
while(rs.next()){
String author=rs.getString( "author ");
result.addElement(author);
String subject=rs.getString( "subject ");
result.addElement(subject);
String email=rs.getString( "email ");
result.addElement(email);
String content=rs.getString( "content ");
result.addElement(content);
}
rs.close();
stmt.close();
con.close();
}catch(Exception e){}
return result;
}
}
index.jsp代码：
<%@page contentType= "text/html;charset=gb2312 "import= "java.util.* " %>
<jsp:useBean id= "info " scope= "page " class= "testbeans.GetUserInfo ">
</jsp:useBean>
<%
Vector vec=info.getInfo();
int count=vec.size();
out.print(count);
String str=new String( " ");
for(int i=0;i <count;i++)
{
str+=vec.elementAt(i).toString();
}
if(count!=0)
{out.print(str);}
%>
编译时报错：
org.apache.jasper.JasperException: Exception in JSP: /index.jsp:11
8: String str=new String( " ");
9: for(int i=0;i <count;i++)
10: {
11: str+=vec.elementAt(i).toString();
12: }
13: if(count!=0)
14: {out.print(str);}
如果不用循环，只写str=vec.elementAt(1).toString()可以得出正确结束，但是用循环却不行，请高手帮我纠正一下，谢谢了！
------解决方案--------------------
试试这样：
8: String str= " ";
9: for(int i=0;i <count;i++)
10: {
11: str+=(String)vec.get(i);
12: }
13: if(count!=0)
14: {out.print(str);}