java - 如何使用oop概念传递不同数据类型的ArrayList对象？

Question

我正在尝试使用 ArrayList 将值传递到数据库。然后我得到一个异常java.lang.ClassCastException:java.lang.String无法转换为model.OrderModel
这是我如何获取用户的值有人可以检查一下并帮助我做到这一点

DefaultTableModel dtm = (DefaultTableModel) tblOrder.getModel();
    int numRow = dtm.getRowCount();
    int numCol = dtm.getColumnCount();
  try {

    ArrayList<OrderModel> list = new ArrayList<OrderModel>();    
    for(int l = 0;l<numRow;l++){
        for(int j=0;j<numCol;j++){
          list.add((OrderModel) tblOrder.getValueAt(l, j));//this line may be the problem as i think
        }
    } 

    Order or = new Order();
    or.passingValuesToDB(list);

        } catch (Exception e) {
            e.printStackTrace();
        }
    }

这是我的方法

public class Order {
Connection con;
    public void passingValuesToDB(ArrayList<OrderModel> list) {
     try {
        con = new DBconnector().connect();
        String sql = "INSERT INTO order (orderid, customername, item, qty, amount, total) VALUES (?,?,?,?,?,?)";

        PreparedStatement ps = con.prepareStatement(sql);
        for(int i=0;i<list.size();i++){
            ps.setInt(1, list.get(i).getOrderid());
            ps.setString(2, list.get(i).getCustomername());
            ps.setString(3, list.get(i).getItem());
            ps.setDouble(4, list.get(i).getQty());
            ps.setDouble(5, list.get(i).getAmount());
            ps.addBatch();
        }
        ps.executeQuery();
    } catch (SQLException ex) {
        ex.printStackTrace();
    }

    }

我已将所有 getters&Setteres 设置为 OrderModel 类。这是代码

public class OrderModel {
     private int orderid;
     private String customername;
     private String item;
     private double qty;
     private double amount;
     private double total;

      public OrderModel(int orderid,String customername,String item,Double qty,Double amount,Double total){
        this.orderid = orderid;
        this.customername = customername;
        this.item = item;
        this.qty = qty;
        this.amount=amount;
        this.total=total;
    }

    public OrderModel() {
        throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.
    }
    public int getOrderid() {
        return orderid;
    }
    public void setOrderid(int orderid) {
        this.orderid = orderid;
    }
    public String getCustomername() {
        return customername;
    }
    public void setCustomername(String customername) {
        this.customername = customername;
    }
    public String getItem() {
        return item;
    }
    public void setItem(String item) {
        this.item = item;
    }
    public double getQty() {
        return qty;
    }
    public void setQty(double qty) {
        this.qty = qty;
    }
    public double getAmount() {
        return amount;
    }
    public void setAmount(double amount) {
        this.amount = amount;
    }
    public double getTotal() {
        return total;
    }
    public void setTotal(double total) {
        this.total = total;
    }


}

Answer 1

(OrderModel) tblOrder.getValueAt(l, j)是问题所在

ValueAt(l, j)返回一个字符串(表列数据类型)。您无法强制转换 String到 OrderModel对象它们是完全不同的对象。你应该创建一个 OrderModel使用行列值的对象。您可以使用 setter 或直接传递给构造函数。然后您可以将其添加到您的 ArrayList<OrderModel> list

ArrayList<OrderModel> list = new ArrayList<OrderModel>();

for (int l = 0; l < numRow; l++) {

            int orderid = Integer.parseInt(tblOrder.getValueAt(l, 0).toString());
            String customername = tblOrder.getValueAt(l, 1).toString();
            String item = tblOrder.getValueAt(l, 2).toString();
            double qty = Double.parseDouble(tblOrder.getValueAt(l, 3).toString());
            double amount = Double.parseDouble(tblOrder.getValueAt(l, 4).toString());
            double total = Double.parseDouble(tblOrder.getValueAt(l, 5).toString());
            // OrderModel object
            OrderModel ormod1 = new (orderid, customername, item, bla..bla..);
            //then add OrderModel to the list
            list.add(ormod1);

}