java - 当按下 JButton 时，JTable 第二次变为空白

Question

我正在尝试加载文件名以及 JTable 中的一些详细信息，当我第一次按下按钮时，它 loads fine ，但是当我第二次按下同一个按钮时，它 goes blank .

简短示例:

package exampleDemo;

public class JTableExample {

private JFrame frame;
private JTable table_1;

/**
 * Launch the application.
 */
public static void main(String[] args) {
    EventQueue.invokeLater(new Runnable() {
        public void run() {
            try {
                JTableExample window = new JTableExample();
                window.frame.setVisible(true);
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    });
}

public JTableExample() {
    initialize();
}

    public void showEmptyTable() {
        final String[] colNames = {"Sl.no.", "File Name", "Size", "Last Modified", "PO", "LN", "SI", "MS", "PT"};
        final String[][] emptyData = {
            {"", "", "", "", "", "", "", "", "",},
            {"", "", "", "", "", "", "", "", "", },
            {"", "", "", "", "", "", "", "", "", },
            {"", "", "", "", "", "", "", "", "", },
            {"", "", "", "", "", "", "", "", "", },};
    table_1.setModel(new DefaultTableModel(emptyData, colNames));
    frame.getContentPane().add(table_1);
    JScrollPane scrollPane = new JScrollPane(table_1);
    scrollPane.setBounds(81, 162, 830, 180);
    frame.getContentPane().add(scrollPane);
};

private void initialize() {
    frame = new JFrame();
    frame.setBounds(100, 100, 1002, 576);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.getContentPane().setLayout(null);

    table_1 = new JTable();
    table_1.setBounds(81, 162, 830, 180);
    frame.getContentPane().add(table_1);

    JButton btnNewButton = new JButton("New button");
    btnNewButton.addActionListener(new ActionListener() {
        public void actionPerformed(ActionEvent arg0) {
            table_1.repaint(); 
            showEmptyTable();
        }
    });
    btnNewButton.setBounds(578, 70, 89, 23);
    frame.getContentPane().add(btnNewButton);
    }
}

Answer 1

快速浏览一下您的代码，我会发现您正在以错误的方式处理此问题:每次单击按钮时，您实际上都会重建一个新的表模型，我怀疑(尽管这只是预感)时刻)是因为每次单击该按钮时，您都会通过新的滚动面板将同一个表添加到主 JFrame - 每次。

您想要做的是在加载框架期间初始化表格及其模型。然后，如果您想清除该表，只需获取对该表模型的引用并操作现有模型即可。就是这样 - 不需要创建一个全新的模型；无需通过滚动面板添加新表格。

因此，在您的情况下，我要做的就是在构造函数中添加一行:

public YourClassName() {
  initialize();
  initializeYourTable();
}

然后 initializeYourTable() 看起来像这样:

private void initSearchTable() {
    final String[] colNames = {"Sl.no.", "File Name", "Size", "Last Modified", "PO", "LN", "SI", "MS", "PT"};
    //PO: Part Order
    //LN: Line Number
    //SI: Serial Number
    //MS: Material Supplier
    //PT: Part Item 
    final String[][] emptyData = {
        {"", "", "", "", "", "", "", "", "",},
        {"", "", "", "", "", "", "", "", "",},
        {"", "", "", "", "", "", "", "", "",},
        {"", "", "", "", "", "", "", "", "",},
        {"", "", "", "", "", "", "", "", "",},};
    table_3.setModel(new DefaultTableModel(emptyData, colNames));
    //frmViperManufacturingRecord.getContentPane().add(table_3); <-- NB this should be commented out!!
    table_3.setAutoResizeMode(JTable.AUTO_RESIZE_OFF);
    table_3.getColumnModel().getColumn(0).setPreferredWidth(40);
    table_3.getColumnModel().getColumn(1).setPreferredWidth(290);
    table_3.getColumnModel().getColumn(2).setPreferredWidth(80);
    table_3.getColumnModel().getColumn(3).setPreferredWidth(178);
    table_3.getColumnModel().getColumn(4).setPreferredWidth(25);
    table_3.getColumnModel().getColumn(5).setPreferredWidth(25);
    table_3.getColumnModel().getColumn(6).setPreferredWidth(25);
    table_3.getColumnModel().getColumn(7).setPreferredWidth(25);
    table_3.getColumnModel().getColumn(8).setPreferredWidth(25);
    JScrollPane scrollPane = new JScrollPane(table_3);
    scrollPane.setBounds(324, 209, 713, 160);
    frmViperManufacturingRecord.getContentPane().add(scrollPane);
}

要清除表格，您可以使用此 shortcut :

private void resetTable() {
    DefaultTableModel model = (DefaultTableModel)table_3.getModel();
    model.setRowCount(0);
}

因此您需要更改您的actionPerformed:

public void actionPerformed(ActionEvent arg0) {
  table_3.repaint();
  //showEmptyTable();
  resetTable();
}