java - JTable -> TableModeListener

Question

我的这个 JTable 有一个 DefaultTableModel 作为它的模型。在表上我有几个 swing 组件，JComboBox 和 JCheckBox，通过 DefaultCellEditor 和 DefaultCellRenderer 设置在特定列上.TableModelListener 已添加到表中以捕获可编辑列的更改。其余列将显示所选组件的详细信息，即商品代码 -> 商品价格、商品数量、商品分类等。

我有这个问题，如果 JComboBox(itemCode) 的 selectedItem 发生变化，其他 JComboBox(itemClassification) 的项目也会发生变化。但随着其他 JComboBox 的变化，我需要在同一张表上显示商品价格。此更改重新触发 valueChanged 方法，该方法使 valueChanged 无限循环。

我怎样才能摆脱无限循环呢？

Answer 1

一种方法是检查更新事件以查看该事件针对的是哪一列，并忽略自动更新的列:

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.*;
import javax.swing.table.*;

public class TableProcessing extends JPanel implements TableModelListener
{
    public TableProcessing()
    {
        String[] columnNames = {"Item", "Quantity", "Price", "Cost"};
        Object[][] data =
        {
            {"Bread", new Integer(1), new Double(1.11), new Double(1.11)},
            {"Milk", new Integer(1), new Double(2.22), new Double(2.22)},
            {"Tea", new Integer(1), new Double(3.33), new Double(3.33)},
            {"Cofee", new Integer(1), new Double(4.44), new Double(4.44)}
        };

        DefaultTableModel model = new DefaultTableModel(data, columnNames)
        {
            //  Returning the Class of each column will allow different
            //  renderers to be used based on Class
            @Override
            public Class getColumnClass(int column)
            {
                return getValueAt(0, column).getClass();
            }

            //  The Cost is not editable
            @Override
            public boolean isCellEditable(int row, int column)
            {
                return (column == 3) ? false : true;
            }
        };
        model.addTableModelListener( this );

        JTable table = new JTable( model );
        table.setPreferredScrollableViewportSize(table.getPreferredSize());

        JScrollPane scrollPane = new JScrollPane( table );
        add( scrollPane );

        String[] items = { "Bread", "Milk", "Tea", "Coffee" };
        JComboBox<String> editor = new JComboBox<String>( items );

        DefaultCellEditor dce = new DefaultCellEditor( editor );
        table.getColumnModel().getColumn(0).setCellEditor(dce);
    }

    /*
     *  The cost is recalculated whenever the quantity or price is changed
     */
    public void tableChanged(TableModelEvent e)
    {
        if (e.getType() == TableModelEvent.UPDATE)
        {
            int row = e.getFirstRow();
            int column = e.getColumn();

            if (column == 1 || column == 2)
            {
                TableModel model = (TableModel)e.getSource();
                int quantity = ((Integer)model.getValueAt(row, 1)).intValue();
                double price = ((Double)model.getValueAt(row, 2)).doubleValue();
                Double value = new Double(quantity * price);
                model.setValueAt(value, row, 3);
            }
        }
    }

    private static void createAndShowGUI()
    {
        JFrame frame = new JFrame("Table Model Listener");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.add(new TableProcessing());
        frame.pack();
        frame.setLocationByPlatform( true );
        frame.setVisible( true );
    }

    public static void main(String[] args) throws Exception
    {
        EventQueue.invokeLater( () -> createAndShowGUI() );
/*
        EventQueue.invokeLater(new Runnable()
        {
            public void run()
            {
                createAndShowGUI();
            }
        });
*/
    }
}