swing - 使用新数据刷新 Jtable

Question

1. 我有加载按钮，将数据加载到 jtable
2. 我能够将新数据加载到 jtable。

3. 但是当我重新加载数据并单击 jcheckbox 时，会出现旧数据。 我正在使用 defaulttablemodel 选项。请运行 prog 并帮助我哪里出错了。

   import java.awt.BorderLayout;
   import java.awt.EventQueue;
   import java.awt.event.ActionEvent;
   import java.awt.event.ActionListener;
   import javax.swing.JButton;
   import javax.swing.JComponent;
   import javax.swing.JFrame;
   import javax.swing.JPanel;
   import javax.swing.JScrollPane;
   import javax.swing.JTable;
   import javax.swing.table.DefaultTableModel;
   
   public class MainWindow extends JFrame {
   JTable table;
   private static final int CHECK_COL = 3;
       String[] columnNames = {
       "Country", "Capital", "Population in Millions", "Democracy"};
       Object[][] data = {
       {"USA", "Washington DC", 280, false},
       {"Canada", "Ottawa", 32, false},
       {"United Kingdom", "London", 60, false},
       {"Germany", "Berlin", 83, false},
       {"France", "Paris", 60, false},
       {"Norway", "Oslo", 4.5, false},
       {"India", "New Deli", 1046, false}
       };
       DefaultTableModel dtm ;
       // static JScrollPane scrollpane= new JScrollPane();
       public MainWindow() {
       setTitle("Marking of data");
       setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        JButton button1 = new JButton("load");
       button1.addActionListener(new ActionListener() {
       public void actionPerformed(ActionEvent e) {
           if(dtm!=null){
               System .out .println("NOT EMPTY");
               int c = dtm.getRowCount();
           // for (int i=c-1; i>=0; i--)
           // {
               // dtm.removeRow(i);
               // table.revalidate();
           // }
               loadtable();
                }
           if(dtm==null){
               System .out .println("EMPTY");
               loadtable();
           }
         }
         });
   
         JButton button = new JButton("check");
         button.addActionListener(new ActionListener() {
         @Override
         public void actionPerformed(ActionEvent e) {
           for (int row = 0; row < table.getRowCount(); row++) {
               Boolean b = ((Boolean) table.getValueAt(row, CHECK_COL));
               if (b.booleanValue()) {
                   System.out.print("row " + row + " is " + b + ": ");
                   for (int col = 0; col < table.getColumnCount(); col++) {
                       System.out.print(table.getValueAt(row, col) + " ");
                   }
                   System.out.println();
               }
           }
         }
         });
         JPanel buttonpanel1 = new JPanel();
         buttonpanel1.add(button1);
         JPanel buttonpanel = new JPanel();
         buttonpanel.add(button);
         add(buttonpanel, BorderLayout.SOUTH);
         add(buttonpanel1, BorderLayout.NORTH);
         pack();
         setLocationByPlatform(true);
         setVisible(true);
         }
         public void loadtable(){
       dtm = new DefaultTableModel(data, columnNames) {
           @Override
           public Class getColumnClass(int col) {
               return getValueAt(0, col).getClass();
           }
           @Override
           public boolean isCellEditable(int rowIndex, int colIndex) {
               return (colIndex == CHECK_COL);
           }
         };
         table = new JTable(dtm);
         JScrollPane scrollpane = new JScrollPane(table);
         add(scrollpane, BorderLayout.CENTER);
         pack();
         setVisible(true);
         }
   
   
        public static void main(String args[]) {
        EventQueue.invokeLater(new Runnable() {
        @Override
        public void run() {
           new MainWindow();
         }
        });
        }
         }
   

需要帮助。请

Answer 1

默认表模型将数据从二维数组复制到自己的向量中。

每次按下加载按钮时，都会使用相同的数据创建一个新的默认表模型，并为新表模型的向量制作一个新副本。

每次按下加载按钮时，您的代码都会重置表模型，因此当然会出现旧数据。