Question

java连接access数据库,随机查询,出现参数不足,期待值是2

import java.sql.*;
import java.util.LinkedList;
public class Example
{ public static void main(String args[])
{ LinkedList list=new LinkedList();
Connection con;
Statement sql;
ResultSet rs;
try
{ Class.forName("sun.jbdc.obdc.JdbcOdbcDriver");
}
catch(ClassNotFoundException e) {}
try
{ con=DriverManager.getConnection("jdbc:odbc:sun","","");
sql=con.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE,ResultSet.CONCUR_READ_ONLY);
rs=sql.executeQuery("SELECT name,math FROM chenjibiao");
rs.last();
int lownumber=rs.getRow();
int number=lownumber;
for(int i=1;i<=number;i++)
{ list.add(new Integer(i));
}
double sum=0;
int k=3;
int 抽取数目=k;
while(k>0)
{ int i=(int)(Math.random()*list.size());
int index=(( Integer)list.get(i)).intValue();
rs.absolute(index);
System.out.print("姓名:"+rs.getString(1));
System.out.println("数学:"+rs.getString(2));
int math=rs.getInt("math");
sum=sum+math;
k--;
list.remove(i);
}
System.out.println("抽取的数学平均成绩:"+sum/抽取数目);
con.close();
}
catch(SQLException e)
{System.out.println(e);
}
}
}
不行啊，我刚接触java,还请高手指点。
是不是数据库连接时出错了？？？

Answer 1

连接未打开。。。conn.open();

Answer 2

希望你能自己解决这个问题。