java - 添加行不起作用

Question

我正在尝试创建一个项目列表，当我点击 + 按钮时，会添加一个新行。问题是，尽管调用了用于添加项目的函数，但由于某种原因面板永远不会更新。这是我的代码:

    public static GridBagConstraints getContraint() {
        GridBagConstraints c = new GridBagConstraints();
        c.insets = new Insets(3, 3, 3, 3);
        c.weightx = 1.0/3;
        c.fill = GridBagConstraints.HORIZONTAL;
        c.anchor = GridBagConstraints.CENTER;
        c.gridy = 1;
        return c;
    }
    public static void addRow(JPanel j, GridBagConstraints c) {
        c.gridy++;
        System.out.println("Test");
        for (int h = 0; h < 3; h++) {
            c.gridx = h;
            JTextField f = new JTextField();
            j.add(f, c);
        }
    }
    public static JPanel createLayout(int rows) {
        final JPanel product = new JPanel(new BorderLayout());
        final JPanel  list = new JPanel(new GridBagLayout());
        String[] lables = {"School    ", "Advanced #", "Novice #   "};
        double weight = .3333333333333;

        final GridBagConstraints c = getContraint();
        for (int j = 0; j < lables.length; j++) {
            c.gridx = j;
            JLabel f = new JLabel(lables[j]);
            list.add(f, c);
        }

        for (int i = 0; i < rows; i++) {
            addRow(list, c);
        }
//      c.gridy++;
//      c.gridx = 0;
//      c.gridwidth = GridBagConstraints.REMAINDER;
//      c.anchor = GridBagConstraints.NORTHWEST;
//      c.fill = GridBagConstraints.NONE;

        JPanel b = new JPanel();
        JButton add = new JButton("+");
        add.addActionListener(new ActionListener() {

            public void actionPerformed(ActionEvent e) {
                addRow(list, c);
                list.repaint();

            }
        });
        b.add(add);
        JButton delete = new JButton("-");
        b.add(delete);
        product.add(b, BorderLayout.SOUTH);
        product.add(list, BorderLayout.CENTER);
        return product;
    }
    public static void printDebates(ArrayList<Judge> d) {
        for (Judge j : d) {
            System.out.printf("Judge: %s ", j.toString() + (j.getDebates().get(0).isAdvanced() ? 'A' : 'N'));
            for (Debate de : j.getDebates()) {
                System.out.printf("Round: %s ", de != null ? de.toString() : "null");
            }
            System.out.print("\n");
        }
    }
    public static void main(String[] args) throws IOException {
        JFrame frame = new JFrame("Debate Calculator");
        JPanel debates = new JPanel();
        frame.add(createLayout(5), BorderLayout.NORTH);
        frame.pack();
        frame.setVisible(true);
    }

Answer 1

添加新组件后，JPanel j 需要重新验证 和重新绘制:

j.revalidate();
j.repaint();

注意:JTable 组件已提供添加行的功能