连接Oracle数据库出的问题 总是出问题 求助

这是程序：

package bb;
import java.sql.*;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.SQLException;

public class cc {

public static void main(String[] args) {

      String driver="oracle.jdbc.driver.OracleDriver";
      String url="jdbc:oracle:thin:@localhost:1521:ora9";
      String username="scott";
      String password="tiger";
      String sql="insert into tt(id,name)values(?,?)";
     
      try {
Class.forName(driver);
Connection conn=DriverManager.getConnection(url, username, password);
PreparedStatement prst=conn.prepareStatement(sql);

prst.setString(1,"1005");
prst.setString(2, "gfjh");
prst.executeUpdate();
prst.close();
conn.close();
} catch (ClassNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}


运行后总是出现这个错误：

Exception in thread &quo