为Java集合实现AbstractTableModel

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问题描述

我正在尝试为名为clients的集合实现 AbstractTableModel 但我仍然收到add方法的错误required variable found value。
这是我的代码：

I'm trying to implement an AbstractTableModel for a collection named "clients" but I keep receiving the error "required variable found value" for the "add" method.Here is my code:

我很抱歉造成了混乱。 add方法是为了在表中添加一个新客户端（我指的是一个新行）。我不想在集合中添加新客户端。

I'm sorry for the confusion created. The add method is meant to add a new client in the table (by that I mean a new row). I don't want to add a new client to the collection.

class ModelTabel extends AbstractTableModel{

    public int getRowCount() {
        return clients.size();
    }

    public int getColumnCount() {
        return 4;
    }

    public Object getValueAt(int row, int column) {
        Client c = clients.get(row-1);
        switch(column){
            case 0: return c.getName();
            case 1: return c.getSurname();
            case 2: return c.getID();
            case 3: return c.getPhone();
            default:return "ERROR";
        }
    }

    public void add(Client c) {
        clients.get(clients.size()++) = a;
        fireTableDataChanged();
        }
    }

推荐答案

我相信这是与相同的问题......你的变量赋值是相反的。

I believe this is the same problem as this question... your variable assignment is reversed.

它应该是（虽然这段代码仍然不正确 - 见下文）：

It should be (although this code is still incorrect - see below):

a = clients.get(clients.size()++);

编辑：Prabhakaran已经回答了这个问题，但显然人们觉得有必要对我的答案进行评价。我想我确实解决了原来的问题，但我很欣赏我的代码示例仍然不正确，所以我会尝试提供更完整的答案：

this was already answered by Prabhakaran, but apparently people felt the need to downvote my answer.. I think I did address the original question, but I appreciate that my code sample was still incorrect, so I will try to provide a more complete answer:

首先，至于未找到所需变量错误，如果你谷歌它你会看到其他SO问题作为第一个命中。 clients.get（clients.size（）++）不是变量，因此您无法为其分配内容。我不确定在你的代码中声明了 a ，但是假设它是一个变量，因此我建议撤销赋值。

First of all, as to the "required variable not found" error, if you google it you will see that other SO question as the first hit. clients.get(clients.size()++) is not a variable, so you can't assign things to it. I am not sure where a is declared in your code, but assume that it is a variable and thus my suggestion of reversing the assignment.

接下来，对于 clients.get（clients.size（）++）行，正如其他人提到或暗示的那样 - VAR ++ 相当于 VAR = VAR + 1 ，因此再次进行分配操作。在这种情况下， clients.size（）不是变量，因此您无法递增它。如果你想要 clients.size（）+ 1 索引，你可以编写： a = clients.get（clients.size（）+ 1 ） ...但是这将抛出 ArrayIndexOutOfBoundsException ，因为你试图访问客户端的元素超出当前大小！

Next, for the clients.get(clients.size()++) line, as others have mentioned or alluded to - VAR++ is equivalent to VAR = VAR + 1, so again is an assignment operation going on. In this case, clients.size() is not a variable, so you can not increment it. If you wanted the clients.size() + 1 index, you could have written: a = clients.get(clients.size() + 1)... but that will throw an ArrayIndexOutOfBoundsException, because you're trying to access an element of clients beyond its current size!

这就是Prabhakaran重写你的方法的原因，将该行更改为 clients.add （c）调用 - 因为它似乎符合该方法的原始意图。

That is why Prabhakaran rewrote your method as they did, changing that line to a clients.add(c) call - as it seemed to fit the original intent of the method.

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Clients