在JFrame中打包三个JPanel

Question

我想要适应三个JPanel（dataPanel，tablePanel和btnPanel），所以这就是我得到的：

问题是中间面板（tablePanel）在顶部裁剪，标题不可见。我还添加了一个JScrollPane，它也没有出现。我是Java Swing的新手，所以这是我的代码：

JFrame frame = new JFrame("Crear pedido");
frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
frame.setSize(500,500);
//frame.setSize(300, 150);
// or frame.pack() to "pack" all the components in this frame
frame.setVisible(true);  // show it
frame.setResizable(false);
frame.setLocationRelativeTo(null);

JPanel dataPanel = new JPanel();
dataPanel.setLayout(new BoxLayout(dataPanel, BoxLayout.X_AXIS));
//frame.add((Component) BorderFactory.createEmptyBorder(30,0,0,0));
dataPanel.setBorder(new EmptyBorder(20,0,30,0));
frame.add(dataPanel, BorderLayout.NORTH);

JLabel id = new JLabel("ID:");
JLabel date = new JLabel("Fecha:");
JLabel dept = new JLabel("Departamento");

JTextField idInput = new JTextField (5);
idInput.setMaximumSize(new Dimension(70,25));
JFormattedTextField dateInput = new JFormattedTextField(df);
dateInput.setMaximumSize(new Dimension(70,25));
JComboBox deptSelect = new JComboBox(selectArray);
deptSelect.setMaximumSize(new Dimension(70,25));

id.setAlignmentX(Component.CENTER_ALIGNMENT);
date.setAlignmentX(Component.CENTER_ALIGNMENT);
dept.setAlignmentX(Component.CENTER_ALIGNMENT);
idInput.setAlignmentX(Component.CENTER_ALIGNMENT);
dateInput.setAlignmentX(Component.CENTER_ALIGNMENT);
deptSelect.setAlignmentX(Component.CENTER_ALIGNMENT);

dataPanel.add(Box.createRigidArea(new Dimension(30,0)));
dataPanel.add(id);
dataPanel.add(idInput);
dataPanel.add(Box.createRigidArea(new Dimension(30,0)));
dataPanel.add(date);
dataPanel.add(dateInput);
dataPanel.add(Box.createRigidArea(new Dimension(30,0)));
dataPanel.add(dept);
dataPanel.add(deptSelect);

JPanel productPanel = new JPanel();
productPanel.setLayout(new BoxLayout(productPanel, BoxLayout.Y_AXIS));
frame.add(productPanel, BorderLayout.CENTER);

JTable table = new JTable(data, headerProductos);
table.setMaximumSize(new Dimension(500,250));
table.setAlignmentX(Component.CENTER_ALIGNMENT);
table.setAlignmentY(Component.CENTER_ALIGNMENT);
table.getTableHeader().setForeground(Color.blue);
table.setEnabled(false);

JScrollPane scroll = new JScrollPane(table);
productPanel.add(table);
table.add(scroll);

JPanel btnPanel = new JPanel();
btnPanel.setLayout(new BoxLayout(btnPanel, BoxLayout.X_AXIS));
btnPanel.setBorder(new EmptyBorder(150,0,0,0));
frame.add(btnPanel, BorderLayout.SOUTH);

Answer 1

替换行：

    productPanel.add(table);
    table.add(scroll);

有：

    productPanel.add(scroll);