如何在此表上执行添加操作？

import javax.swing.*; import javax.swing.event.*; import java.awt.*; import java.awt.event.*; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import javax.swing.JComponent; import javax.swing.SwingUtilities; import net.java.dev.designgridlayout.DesignGridLayout; import java.io.*; import net.java.dev.designgridlayout.Tag; import javax.swing.JButton; import javax.swing.JTable; import javax.swing.table.DefaultTableModel; import javax.swing.table.TableModel; import javax.swing.table.AbstractTableModel; import javax.swing.table.*; import java.sql.*; import javax.swing.table.TableColumn; class table1 { JFrame JF; Container C; JPanel JP; JLabel creditLabel; JComboBox credit; String[] Credit = { "Vasan Phalke", "Pansare", "Anil Kg", "Suresh", "Total Credit", "" }; String[] Names = { "Name", "Qty", "Rate/ Kg", "Total Amt." }; JTable table; DefaultTableModel model; JScrollPane scrollPane; public table1() { JF = new JFrame(); JP = new JPanel(); C = JF.getContentPane(); C.setLayout(new BorderLayout()); JF.pack(); JF.setLocationRelativeTo(null); JF.setVisible(true); DesignGridLayout layout = new DesignGridLayout(JP); creditLabel = new JLabel("Credit"); credit = new JComboBox(Credit); model = new DefaultTableModel(Names, 6) { @Override public Class getColumnClass(int columnIndex) { switch (columnIndex) { case 0: return String.class; case 1: return Integer.class; case 2: case 3: return Double.class; } return super.getColumnClass(columnIndex); } public Object getValueAt(int row, int column) { if (column == 3) { Integer i = (Integer) getValueAt(row, 1); Double d = (Double) getValueAt(row, 2); if (i != null && d != null) { return i * d; } else { return 0 * 0; } } return super.getValueAt(row, column); } public boolean isCellEditable(int arg0, int arg1) { return true; } public void setValueAt(Object aValue, int row, int column) { super.setValueAt(aValue, row, column); fireTableCellUpdated(row, 3); } }; table = new JTable(model); { TableColumn nameColumn = table.getColumnModel().getColumn(0); nameColumn.setCellEditor(new DefaultCellEditor(credit)); } scrollPane = new JScrollPane(table); layout.row().grid(creditLabel); layout.emptyRow(); layout.row().grid().add(scrollPane); C.add(JP); } public static void main(String args[]) { new table1(); } } 

我想要Total Amt的总和。 列出现在单元格上（5,4）。 我尝试了一些代码，但是失败了，请在下面添加显示附加图像的代码。 从过去的5个小时开始，我被困在这桌子上。 提前致谢。

Answer 1

下面显示了包含此方法的示例的简化变体。 请注意以下几点：

• 虽然JTable 不是电子表格，但可以动态更新单元格以帮助理解。 使用TableModelListener更新相关的视图组件。

• TableModel应该为可能的最少数量的单元格触发事件; fireTableDataChanged()用于这个小型固定大小模型的方便性。

• 始终pack()封闭的Window并最后使setVisible() 。

• 应该仅在事件派发线程上构造和操作Swing GUI对象。

• 使用通用编码约定。

代码经测试：

 import java.awt.EventQueue; import javax.swing.*; import javax.swing.JTable; import javax.swing.table.DefaultTableModel; import javax.swing.table.TableColumn; public class Table1 { JFrame frame; JComboBox credit; String[] rowNames = { "Vasan Phalke", "Pansare", "Anil Kg", "Suresh", "Total Credit", ""}; String[] colNames = {"Name", "Qty", "Rate/ Kg", "Total Amt."}; JTable table; DefaultTableModel model; JScrollPane scrollPane; public Table1() { frame = new JFrame(); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); credit = new JComboBox<>(rowNames); model = new DefaultTableModel(colNames, 6) { @Override public Class getColumnClass(int columnIndex) { switch (columnIndex) { case 0: return String.class; case 1: return Integer.class; case 2: return Double.class; case 3: return Double.class; } return super.getColumnClass(columnIndex); } @Override public Object getValueAt(int row, int col) { if (col == 3 & row == 5) { double sum = 0; for (int i = 0; i < 5; i++) { sum += ((Double) getValueAt(i, 3)).doubleValue(); } return sum; } if (col == 3 & row != 5) { Integer i = (Integer) getValueAt(row, 1); Double d = (Double) getValueAt(row, 2); if (i != null && d != null) { return i * d; } else { return 0d; } } return super.getValueAt(row, col); } @Override public void setValueAt(Object aValue, int row, int col) { super.setValueAt(aValue, row, col); fireTableDataChanged(); } @Override public boolean isCellEditable(int row, int col) { return col != 3; } }; table = new JTable(model); TableColumn nameColumn = table.getColumnModel().getColumn(0); nameColumn.setCellEditor(new DefaultCellEditor(credit)); scrollPane = new JScrollPane(table); frame.add(new JScrollPane(table)); frame.pack(); frame.setLocationRelativeTo(null); frame.setVisible(true); } public static void main(String args[]) { EventQueue.invokeLater(new Runnable() { @Override public void run() { new Table1(); } }); } }