Question

TableModelListener（第87行/ HERE-1）是否干扰了我的JTable的addRow方法（第139行，HERE-2）？如果是这样，我该如何解决？

这段代码会编译但是当我使用＆＃34;添加行＆＃34;时会抛出错误。按钮。错误是：（堆栈跟踪的时间要长得多，但我已经将它缩减为关于我的类而不是java API的行）

线程中的异常＆＃34; AWT-EventQueue-0＆＃34; java.lang.ArrayIndexOutOfBoundsException：

在HPLC.addRow（HPLC.java:142）

at HPLC.lambda $ new $ 1（HPLC.java:109）

这只是一个问题，因为我已经添加了TableModelListener。

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

class HPLC extends JFrame
{
    public static void main (String [] args)
    {
        new HPLC();
    }
    HPLC()
    {
        //create window
        JFrame frame = new JFrame();
        frame.setTitle("HPLC Calculator");
        frame.setSize(500,750);
        frame.setResizable(false);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        JPanel panel = new JPanel();
        panel.setLayout(new GridBagLayout());

        //row 0
        JLabel title = new JLabel("HPLC Gradient Calculator");
        gridBagAdd(panel, title, 0,0,4,1, GridBagConstraints.CENTER);

        //row 1
        JLabel flowLabel = new JLabel("Flow rate");
        gridBagAdd(panel, flowLabel, 0,1,1,1, GridBagConstraints.CENTER);

        JTextField flow = new JTextField(5);
        gridBagAdd(panel, flow, 1,1,1,1, GridBagConstraints.CENTER);

        JLabel mlMinLabel = new JLabel("ml/min");
        gridBagAdd(panel, mlMinLabel, 2,1,1,1, GridBagConstraints.CENTER);

        //row 2
        JLabel numInjLabel = new JLabel("Number of injections");
        gridBagAdd(panel, numInjLabel, 0,2,1,1, GridBagConstraints.CENTER);

        JTextField numInj = new JTextField(5);
        gridBagAdd(panel, numInj, 1,2,1,1, GridBagConstraints.CENTER);

        //row 3
        JLabel volALabel = new JLabel("Volume of A");
        gridBagAdd(panel, volALabel, 0,3,1,1, GridBagConstraints.CENTER);

        JTextField volA = new JTextField(5);
        volA.setEditable(false);
        gridBagAdd(panel, volA, 1,3,1,1, GridBagConstraints.CENTER);

        JLabel volBLabel = new JLabel("Volume of B");
        gridBagAdd(panel, volBLabel, 2,3,1,1, GridBagConstraints.CENTER);

        JTextField volB = new JTextField(5);
        volB.setEditable(false);
        gridBagAdd(panel, volB, 3,3,1,1, GridBagConstraints.CENTER);

        //row 4
        JButton calculate = new JButton("calculate");
        gridBagAdd(panel, calculate, 0,4,1,1, GridBagConstraints.CENTER);

        JButton addRow = new JButton("add row");
        gridBagAdd(panel, addRow, 1,4,1,1, GridBagConstraints.CENTER);

        JButton removeRow = new JButton("remove row");
        gridBagAdd(panel, removeRow, 2,4,1,1, GridBagConstraints.CENTER);

        //the gradient table
        String[] columns = {"Time", "%A", "%B"};
        DefaultTableModel model = new DefaultTableModel(columns, 2)
        {
            public boolean isCellEditable(int row, int column)
            //this overrides the default method to suit these conditions to make the 3rd column read only
            {
                if (column == 2)
                    return false;
                return true;
            }
        };
        JTable table = new JTable(model);
        table.setFillsViewportHeight(true);
        JScrollPane tablePane = new JScrollPane(table);
        gridBagAdd(panel, tablePane, 0,5,4,4, GridBagConstraints.CENTER);
        table.getModel().addTableModelListener(new TableModelListener()
   //HERE-1 {
                public void tableChanged(TableModelEvent e)
                //overriding the TableModelListener method
                {
                    //the basics in order to get the table cell
                    int row = e.getFirstRow();
                    int column = e.getColumn();
                    TableModel model = (TableModel)e.getSource();
                    String ColumnName = model.getColumnName(column);
                    Object data = model.getValueAt(row, column);

                    //what i do with that cell
                    volB.setText(data.toString());
                }   
            });

        //button methods
        calculate.addActionListener(e -> calculate(model, volA));
        addRow.addActionListener(e -> addRow(model));
        removeRow.addActionListener(e -> removeRow(model));

        //make visible
        frame.add(panel);
        frame.setVisible(true);
    }
    //method for placement of components
    private void gridBagAdd(JPanel p, JComponent c, int x, int y, int width, int height, int align)
    {
        GridBagConstraints gc = new GridBagConstraints();
        gc.gridx = x;
        gc.gridy = y;
        gc.gridwidth = width;
        gc.gridheight = height;
        gc.weightx = 100;
        gc.weighty = 100;
        gc.insets = new Insets(5,5,5,5);
        gc.anchor = align;
        gc.fill = GridBagConstraints.NONE;
        p.add(c, gc);
    }
    //button method execution
    private void calculate(DefaultTableModel model, JTextField volA)
    {
            int rowCount = model.getRowCount();
            String msg = rowCount + " rows";
            volA.setText(msg);
    }
    private void addRow(DefaultTableModel model)
    {
        int colCount = model.getColumnCount();
//HERE-2 Object [] newRow = new Object[colCount];
        model.addRow(newRow);
    }
    private void removeRow(DefaultTableModel model)
    {
        int rowCount = model.getRowCount();
        if (rowCount > 2)
            model.removeRow(rowCount -1);
    }
}

我喜欢我的表格，就是根据表格的内容创建一个数组，以便进行计算。已添加TableModelListener，以便％B列自动完成，总计100％。

我自学成才，这是我第一次看到任何代码。如果您对如何改进我的写作方法有任何建议，我很乐意听到。

Answer 1

您正在添加一个新行，因此TableModelListener将在您的事件中为column属性返回ALL_COLUMNS常量，该值为-1 reference。

int column = e.getColumn(); // here

然后尝试在这里使用-1值：

Object data = model.getValueAt(row, column);

显然无效。

解决方案：在使用之前检查侦听器中的列值。也许您会想要为列值使用int literal。

Answer 2

已添加TableModelListener，以便％B列自动完成以提供总计100％

该事件将告诉您为何生成它。在我看来，您只想在更改单元格中的值时执行代码。

所以代码应该是这样的：

public void tableChanged(TableModelEvent e)
{
    if (e.getType() == TableModelEvent.UPDATE)
    {
        // add processing here
    }
}

有关工作示例，请查看：JTable -> TableModeListener

JTable / DefaultTableModel

2 个答案: