java - 我必须从列表中的一行中获取列 userid

Question

我基本上必须通过单击按钮来删除该行，因此当单击删除按钮时，变量 id 会获取该行。 变量 id 正在获取我选择的行号并使用 for 循环我试图获取用户在单击按钮时选择的行号，然后从该行中提取用户 ID，然后使用准备好的语句将其从数据库中删除。

                  // int id=Integer.parseInt(request.getParameter("user"));
                  // System.out.println("row"+" "+id);

                   List<registerValues> RegList = (ArrayList<registerValues>)session.getAttribute("regList");
                   int sizeOfList=RegList.size();
                   System.out.println("Size of List :"+sizeOfList);
                   List<registerValues> list = new ArrayList<registerValues>();


                   for(int i = 0 ; i<=sizeOfList ; i++) {

                      System.out.println(RegList.get(id-1).toString());


                   }
                    PreparedStatement ps=con.prepareStatement("delete from registration where userid=?");
                    ps.setInt(1,id);

                   int i=ps.executeUpdate();  
                   if(i>0)
                    {
                      RequestDispatcher rd=request.getRequestDispatcher("welcome.jsp");  
                       rd.include(request,response);
                             }
                   else
                     {
                          RequestDispatcher rd=request.getRequestDispatcher("error.jsp");  



                          rd.include(request,response);
                      }

            }
public class registerValues {
public String name;
public String city;
public String gender;
public String username;
public String password;
public String email;
public String contact_no;
public int userid;

public int getUserid() {
    return userid;
}
public void setUserid(int userid) {
    this.userid = userid;
}
public String getName() {
    return name;
}
public void setName(String name) {
    this.name = name;
}
public String getCity() {
    return city;
}
public void setCity(String city) {
    this.city = city;
}
public String getGender() {
    return gender;
}
public void setGender(String gender) {
    this.gender = gender;
}
public String getUsername() {
    return username;
}
public void setUsername(String username) {
    this.username = username;
}
public String getPassword() {
    return password;
}
public void setPassword(String password) {
    this.password = password;
}
public String getEmail() {
    return email;
}
public void setEmail(String email) {
    this.email = email;
}
public String getContact_no() {
    return contact_no;
}
public void setContact_no(String contact_no) {
    this.contact_no = contact_no;
}

}

这是从数据库中选择我的值的地方 公共(public)静态列表寄存器值() {

         Connection conn = null;
         PreparedStatement pst = null;
         ResultSet rs = null;
         values.registerValues registerobject=null;
         List<registerValues> list = new ArrayList<registerValues>();
         try {
            conn = getDbConnection();
             pst = conn.prepareStatement("Select name,city,gender,username,password,email,contact_no,userid from registration");

             rs = pst.executeQuery();


             while(rs!=null&&rs.next()) {

                registerobject= new registerValues();
                registerobject.setUserid(rs.getInt("userid"));
                registerobject.setName(rs.getString("name"));
                registerobject.setCity(rs.getString("city"));
                registerobject.setGender(rs.getString("gender"));
                registerobject.setUsername(rs.getString("username"));
                registerobject.setPassword(rs.getString("password"));
                registerobject.setEmail(rs.getString("email"));
                registerobject.setContact_no(rs.getString("contact_no"));

                list.add(registerobject);


                System.out.println("REGISTRATION values present");

             }
             conn.close();  

}

Answer 1

您无法像这样获取 RegList 的值:

 System.out.println(RegList.get(id-1).toString()); //wrong

RegList 是 registerValues 的列表，因此您需要使用 getter 来获取值:

如果你想获取用户ID:

 System.out.println(RegList.getUserid());

请告诉我这是否有帮助。