线程“AWT-EventQueue-0”中的异常 java.lang.ClassCastException: javax.swing.JTable

Exception in thread "AWT-EventQueue-0" java.lang.ClassCastException: javax.swing.JTable

提问by user716775

I have a codewhich when run generates a table in swing form which contains a set of checkboxes which can be selected or unselected

我有一个代码，它在运行时生成一个摆动形式的表格，其中包含一组可以选择或取消选择的复选框

When I click on the Check All tab I am able to select/unselect all the other below check boxes but when i select one of the below checkboxes individually I get this error :

当我单击“全部检查”选项卡时，我可以选择/取消选择以下所有其他复选框，但是当我单独选择以下复选框之一时，出现此错误：

> Exception in thread "AWT-EventQueue-0" java.lang.ClassCastException: javax.swing.JTable
    at com.tps.charts.CheckBoxHeader.handleClickEvent(JTableHeaderCheckBox.java:152)
    at com.tps.charts.CheckBoxHeader.mouseClicked(JTableHeaderCheckBox.java:168)
    at java.awt.AWTEventMulticaster.mouseClicked(Unknown Source)
    at java.awt.AWTEventMulticaster.mouseClicked(Unknown Source)
    at java.awt.AWTEventMulticaster.mouseClicked(Unknown Source)
    at java.awt.AWTEventMulticaster.mouseClicked(Unknown Source)
    at java.awt.AWTEventMulticaster.mouseClicked(Unknown Source) mousePressed......
    at java.awt.AWTEventMulticaster.mouseClicked(Unknown Source)
    at java.awt.AWTEventMulticaster.mouseClicked(Unknown Source)
    at java.awt.AWTEventMulticaster.mouseClicked(Unknown Source)
    at java.awt.Component.processMouseEvent(Unknown Source)
    at javax.swing.JComponent.processMouseEvent(Unknown Source)
    at java.awt.Component.processEvent(Unknown Source)
    at java.awt.Container.processEvent(Unknown Source)
    at java.awt.Component.dispatchEventImpl(Unknown Source)
    at java.awt.Container.dispatchEventImpl(Unknown Source)
    at java.awt.Component.dispatchEvent(Unknown Source)
    at java.awt.LightweightDispatcher.retargetMouseEvent(Unknown Source)
    at java.awt.LightweightDispatcher.processMouseEvent(Unknown Source)
    at java.awt.LightweightDispatcher.dispatchEvent(Unknown Source)
    at java.awt.Container.dispatchEventImpl(Unknown Source)
    at java.awt.Window.dispatchEventImpl(Unknown Source)
    at java.awt.Component.dispatchEvent(Unknown Source)
    at java.awt.EventQueue.dispatchEvent(Unknown Source)
    at java.awt.EventDispatchThread.pumpOneEventForHierarchy(Unknown Source)
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
    at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
    at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
    at java.awt.EventDispatchThread.run(Unknown Source)

The code:

该代码：

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

public class JTableHeaderCheckBox {

    private Object colNames[] = {"", "String", "String"};
    private Object[][] data = {};
    private DefaultTableModel dtm;
    private JTable table;
    private TableColumn tc;

    public void buildGUI() {
        dtm = new DefaultTableModel(data, colNames);
        table = new JTable(dtm);
        for (int x = 0; x < 5; x++) {
            dtm.addRow(new Object[]{false, "Row " + (x + 1) + " Col 2", "Row " + (x + 1) + " Col 3"});
        }
        JScrollPane sp = new JScrollPane(table);
        tc = table.getColumnModel().getColumn(0);
        tc.setCellEditor(table.getDefaultEditor(Boolean.class));
        tc.setCellRenderer(table.getDefaultRenderer(Boolean.class));
        tc.setHeaderRenderer(new CheckBoxHeader(new MyItemListener()));
        JFrame f = new JFrame();
        f.getContentPane().add(sp);
        f.pack();
        f.setLocationRelativeTo(null);
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.setVisible(true);
    }

    private class MyItemListener implements ItemListener {

        @Override
        public void itemStateChanged(ItemEvent e) {
            System.out.println("ItemStateChanged");
            Object source = e.getSource();
            if (source instanceof AbstractButton == false) {
                return;
            }
            boolean checked = e.getStateChange() == ItemEvent.SELECTED;
            for (int x = 0, y = table.getRowCount(); x < y; x++) {
                table.setValueAt(checked, x, 0);
            }
        }
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {

            @Override
            public void run() {
                new JTableHeaderCheckBox().buildGUI();
            }
        });
    }
}

class CheckBoxHeader extends JCheckBox implements TableCellRenderer, MouseListener {

    private static final long serialVersionUID = 1L;
    private CheckBoxHeader rendererComponent;
    private int column;
    private boolean mousePressed = false;

    public CheckBoxHeader(ItemListener itemListener) {
        rendererComponent = this;
        rendererComponent.addItemListener(itemListener);
    }

    @Override
    public Component getTableCellRendererComponent(JTable table, Object value,
            boolean isSelected, boolean hasFocus, int row, int column) {
        if (table != null) {
            JTableHeader header = table.getTableHeader();
            table.addMouseListener(rendererComponent);
            if (header != null) {
                rendererComponent.setForeground(header.getForeground());
                rendererComponent.setBackground(header.getBackground());
                rendererComponent.setFont(header.getFont());
                header.addMouseListener(rendererComponent);
            }
        }
        setColumn(column);
        rendererComponent.setText("Check All");
        setBorder(UIManager.getBorder("TableHeader.cellBorder"));
        return rendererComponent;
    }

    protected void setColumn(int column) {
        this.column = column;
    }

    public int getColumn() {
        return column;
    }

    protected void handleClickEvent(MouseEvent e) {
        if (mousePressed) {
            mousePressed = false;
            JTableHeader header = (JTableHeader) (e.getSource());
            JTable tableView = header.getTable();
            TableColumnModel columnModel = tableView.getColumnModel();
            int viewColumn = columnModel.getColumnIndexAtX(e.getX());
            column = tableView.convertColumnIndexToModel(viewColumn);
            if (viewColumn == this.column && e.getClickCount() == 1 && column != -1) {
                System.out.println(" doClick()......");
                doClick();
            }
        }
    }

    @Override
    public void mouseClicked(MouseEvent e) {
        System.out.println(" mouseClicked()......");
        handleClickEvent(e);
        /* problem occurs from this line */
        ((JTableHeader) e.getSource()).repaint();
    }

    @Override
    public void mousePressed(MouseEvent e) {
        //System.out.println("mousePressed(MouseEvent e).......");
        mousePressed = true;
    }

    @Override
    public void mouseReleased(MouseEvent e) {
        //System.out.println(" mouseReleased()......");
    }

    @Override
    public void mouseEntered(MouseEvent e) {
        //System.out.println(" mouseEntered()......");
    }

    @Override
    public void mouseExited(MouseEvent e) {
        //System.out.println("mouseExited()......");
    }
}

with Exception

有例外

Exception in thread "AWT-EventQueue-0" java.lang.ClassCastException: 
javax.swing.JTable cannot be cast to javax.swing.table.JTableHeader

回答by Vlad

On line 152: JTableHeader header = (JTableHeader)(e.getSource());you are assuming the event is on the table header. You need to check event source's class to see if it's on the header or an individual checkbox.

在第 152 行：JTableHeader header = (JTableHeader)(e.getSource());您假设事件在表头上。您需要检查事件源的类以查看它是在标题上还是在单个复选框上。

回答by dacwe

You are casting the source of the event to a JTableHeader:

您正在将事件源转换为JTableHeader：

JTableHeader header = (JTableHeader) (e.getSource());

and the source is a JTablewhen you click at a cell. I would have two differentlisteners for the header and the cell selection or you can do a hack by checking event.getSource() instanceof ...in your mouse-click-listener.

JTable当您单击单元格时，源是 a 。对于标题和单元格选择，我会有两个不同的侦听器，或者您可以通过检查event.getSource() instanceof ...鼠标单击侦听器来进行破解。