これを行うにはおそらくいくつかの方法があり、最終的にどのようにそれを達成するかについての要件に帰着しますが、私の考えでは、新しい行が追加されました...
たとえば、追加された行が 1 つだけの場合、テーブル全体を反復しても意味がありません。非効率です。
代わりにTableModelListener、テーブル モデルの更新を使用してリッスンし、実行中の合計を更新できます (新しい行の値を既に実行中の合計に追加します)。
import java.awt.BorderLayout;
import java.awt.Component;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.text.NumberFormat;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTable;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
import javax.swing.event.TableModelEvent;
import javax.swing.event.TableModelListener;
import javax.swing.table.DefaultTableCellRenderer;
import javax.swing.table.DefaultTableModel;
public class SubTotalTable {
public static void main(String[] args) {
new SubTotalTable();
}
public SubTotalTable() {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
}
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLayout(new BorderLayout());
frame.add(new TestPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class TestPane extends JPanel {
private JLabel subTotal;
private DefaultTableModel tableModel;
private double runningTally = 0;
public TestPane() {
setLayout(new BorderLayout());
tableModel = new DefaultTableModel(new Object[]{"Price"}, 0);
JTable table = new JTable(tableModel);
table.getColumnModel().getColumn(0).setCellRenderer(new CurrencyRenderer());
add(new JScrollPane(table));
JPanel panel = new JPanel(new GridBagLayout());
GridBagConstraints gbc = new GridBagConstraints();
gbc.gridx = 0;
gbc.weightx = 1;
JButton charge = new JButton("Charge");
charge.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
double subTally = 0;
double tally = runningTally;
int rows = (int) (Math.round(Math.random() * 9) + 1);
for (int row = 0; row < rows; row++) {
double amount = (Math.random() * 99999) + 1;
tableModel.addRow(new Object[]{amount});
tally += amount;
subTally += amount;
}
System.out.println("subTally = " + subTally);
System.out.println("tally = " + tally);
}
});
panel.add(charge, gbc);
gbc.gridx++;
gbc.weightx = 0;
subTotal = new JLabel(getRunningTallyDisplayValue());
panel.add(subTotal, gbc);
add(panel, BorderLayout.SOUTH);
tableModel.addTableModelListener(new TableModelListener() {
@Override
public void tableChanged(TableModelEvent e) {
switch (e.getType()) {
case TableModelEvent.DELETE:
System.out.println("Delete");
break;
case TableModelEvent.INSERT:
System.out.println("Insert");
for (int row = e.getFirstRow(); row <= e.getLastRow(); row++) {
Object value = tableModel.getValueAt(row, 0);
if (value instanceof Double) {
runningTally += (double)value;
}
}
break;
case TableModelEvent.UPDATE:
System.out.println("Update");
break;
}
subTotal.setText(getRunningTallyDisplayValue());
}
});
}
protected String getRunningTallyDisplayValue() {
return NumberFormat.getCurrencyInstance().format(runningTally);
}
@Override
public Dimension getPreferredSize() {
return new Dimension(200, 200);
}
}
public class CurrencyRenderer extends DefaultTableCellRenderer {
public CurrencyRenderer() {
setHorizontalAlignment(JLabel.RIGHT);
}
@Override
public Component getTableCellRendererComponent(JTable table, Object value, boolean isSelected, boolean hasFocus, int row, int column) {
if (value instanceof Double) {
value = NumberFormat.getCurrencyInstance().format(value);
}
super.getTableCellRendererComponent(table, value, isSelected, hasFocus, row, column);
return this;
}
}
}
テーブルの使用方法、特にデータ変更のリッスンをご覧ください