list遍历

public List<Y_Student> studentInformation(Connection conn,Y_user user) throws SQLException{
List<Y_Student> list_Stu = new ArrayList<Y_Student>();

String  sql = "select user_name,class_name,result_mark,user_password FROM"
+ "(select user_name, user_password,class_id,result_mark from y_user a "
+ "right join y_result b on a.user_id=b.user_id where user_name = ? and user_password = ?)c "
+ "LEFT JOIN y_class d on c.class_id=d.class_id ";

PreparedStatement ps = null;
ResultSet rs = null;
String userName = user.getUserName();
int  userPassword = user.getUser_Password(); 

conn = JDBCutility.getConnection();
ps = conn.prepareStatement(sql);
ps.setString(1, user.getUserName());
ps.setInt(2, user.getUser_Password());
rs=ps.executeQuery();
while(rs.next()){
  Y_Student  y_Stu = new Y_Student();//每次均需要新建一个对象    list里面的元素为对象
  y_Stu.setStu_Name(rs.getString("user_Name"));
  y_Stu.setStu_Course(rs.getString("class_name"));
  y_Stu.setStu_score(rs.getString("result_mark"));
  list_Stu.add(y_Stu); 
}
JDBCutility.close(rs, ps, conn);
return list_Stu;

}

这样list遍历才能输出每一个对象

List<Y_Student> list = UserOperate.studentInformation(conn, user);

for (Y_Student y_Stu : list) {

String html = "<tr><td>"+y_Stu.getStu_Name()+"</td><td>"+y_Stu.getStu_Course()+"</td><td>"+String.valueOf(y_Stu.getStu_score())+"</td></tr>";
sbf.append(html);
//System.out.println(y_Stu.getStu_Name()+"|"+y_Stu.getStu_Course()+"|"+String.valueOf(y_Stu.getStu_score()));
}