JTable模型侦听器过早检测插入的行(在绘制它们之前)

Question

我有一个JTable可以由用户动态添加的行.它位于a中JScrollPane,因此当行数足够大时,滚动条变为活动状态.我的愿望是当用户添加新行时,滚动条一直移动到底部,以便在滚动窗格中看到新行.我现在(下面的SSCCE)尝试使用表模型侦听器来检测插入行的时间,并在进行检测时强制滚动条一直向下.然而,似乎这种检测"太早了",因为模型已经更新但是新行还没有实际绘制过,所以会发生的事情是滚动器在插入新行之前一直移动到底部,并且然后将新行插入窗格末端的下方(不可见).

显然这种方法在某种程度上是错误的.什么是正确的方法？

import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;

import javax.swing.BoxLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JScrollBar;
import javax.swing.JScrollPane;
import javax.swing.JSplitPane;
import javax.swing.JTable;
import javax.swing.event.TableModelEvent;
import javax.swing.event.TableModelListener;
import javax.swing.table.DefaultTableModel;

public class TableListenerTest {

    private JFrame frame;
    private JScrollPane scrollPane;
    private JTable table;
    private DefaultTableModel tableModel;

    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {
            public void run() {
                try {
                    TableListenerTest window = new TableListenerTest();
                    window.frame.setVisible(true);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        });
    }

    public TableListenerTest() {
        initialize();
    }

    private void initialize() {
        frame = new JFrame();
        frame.setBounds(100, 100, 450, 200);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.getContentPane().setLayout(new BoxLayout(frame.getContentPane(), BoxLayout.Y_AXIS));

        JSplitPane splitPane = new JSplitPane();
        frame.getContentPane().add(splitPane);

        scrollPane = new JScrollPane();
        scrollPane.setPreferredSize(new Dimension(100, 2));
        splitPane.setLeftComponent(scrollPane);

        tableModel = new DefaultTableModel(new Object[]{"Stuff"},0);
        table = new JTable(tableModel);
        scrollPane.setViewportView(table);
        table.getModel().addTableModelListener(new TableModelListener() {
            public void tableChanged(TableModelEvent e) {
                if (e.getType() == TableModelEvent.INSERT) {
                    JScrollBar scrollBar = scrollPane.getVerticalScrollBar();
                    scrollBar.setValue(scrollBar.getMaximum());
                }
            }
        });

        JButton btnAddRow = new JButton("Add Row");
        btnAddRow.addMouseListener(new MouseAdapter() {
            @Override
            public void mouseClicked(MouseEvent e) {
                tableModel.addRow(new Object[]{"new row"});
            }
        });
        splitPane.setRightComponent(btnAddRow);
    }
}

编辑:根据trashgod的请求更新了下面的SSCCE.但是,如果我将滚动逻辑从表模型侦听器移动到按钮侦听器,那么这个版本仍然不起作用,那么它确实有效!

import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Rectangle;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;

import javax.swing.BoxLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JSplitPane;
import javax.swing.JTable;
import javax.swing.event.TableModelEvent;
import javax.swing.event.TableModelListener;
import javax.swing.table.DefaultTableModel;

    public class TableListenerTest {

        private JFrame frame;
        private JScrollPane scrollPane;
        private JTable table;
        private DefaultTableModel tableModel;

        public static void main(String[] args) {
            EventQueue.invokeLater(new Runnable() {
                public void run() {
                    try {
                        TableListenerTest window = new TableListenerTest();
                        window.frame.setVisible(true);
                    } catch (Exception e) {
                        e.printStackTrace();
                    }
                }
            });
        }

        public TableListenerTest() {
            initialize();
        }

        private void initialize() {
            frame = new JFrame();
            frame.setBounds(100, 100, 450, 200);
            frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
            frame.getContentPane().setLayout(new BoxLayout(frame.getContentPane(), BoxLayout.Y_AXIS));

            JSplitPane splitPane = new JSplitPane();
            frame.getContentPane().add(splitPane);

            scrollPane = new JScrollPane();
            scrollPane.setPreferredSize(new Dimension(100, 2));
            splitPane.setLeftComponent(scrollPane);

            tableModel = new DefaultTableModel(new Object[]{"Stuff"},0);
            table = new JTable(tableModel);
            scrollPane.setViewportView(table);
            table.getModel().addTableModelListener(new TableModelListener() {
                public void tableChanged(TableModelEvent e) {
                    if (e.getType() == TableModelEvent.INSERT) {
                        int last = table.getModel().getRowCount() - 1;
                        Rectangle r = table.getCellRect(last, 0, true);
                        table.scrollRectToVisible(r);
                    }
                }
            });

            JButton btnAddRow = new JButton("Add Row");
            btnAddRow.addMouseListener(new MouseAdapter() {
                @Override
                public void mouseClicked(MouseEvent e) {
                    tableModel.addRow(new Object[]{"new row"});
                }
            });
            splitPane.setRightComponent(btnAddRow);
        }
    }

Answer 1

此示例用于scrollRectToVisible()(有条件地)滚动到最后一个单元格矩形.作为一项功能,您可以单击拇指以暂停滚动并释放以恢复.

private void scrollToLast() {
    if (isAutoScroll) {
        int last = table.getModel().getRowCount() - 1;
        Rectangle r = table.getCellRect(last, 0, true);
        table.scrollRectToVisible(r);
    }
}

附录:我尝试 scrollRectToVisible 过我的SSCCE,它仍然表现出同样的问题.

这Action提供了鼠标和键盘控制:

JButton btnAddRow = new JButton(new AbstractAction("Add Row") {

    @Override
    public void actionPerformed(ActionEvent e) {
        tableModel.addRow(new Object[]{"new row"});
        int last = table.getModel().getRowCount() - 1;
        Rectangle r = table.getCellRect(last, 0, true);
        table.scrollRectToVisible(r);
    }
});

附录:这是您示例中的一个变体,用于说明修订后的布局策略.

/** @see https://stackoverflow.com/a/14429388/230513 */
public class TableListenerTest {

    private static final int N = 8;
    private JFrame frame;
    private JScrollPane scrollPane;
    private JTable table;
    private DefaultTableModel tableModel;

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

            @Override
            public void run() {
                TableListenerTest window = new TableListenerTest();
                window.frame.setVisible(true);
            }
        });
    }

    public TableListenerTest() {
        initialize();
    }

    private void initialize() {
        frame = new JFrame();
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setLayout(new BoxLayout(frame.getContentPane(), BoxLayout.X_AXIS));
        tableModel = new DefaultTableModel(new Object[]{"Stuff"}, 0);
        for (int i = 0; i < N; i++) {
            tableModel.addRow(new Object[]{"new row"});
        }
        table = new JTable(tableModel) {

            @Override
            public Dimension getPreferredScrollableViewportSize() {
                return new Dimension(200, table.getRowHeight() * N);
            }
        };
        scrollPane = new JScrollPane();
        scrollPane.setViewportView(table);
        JButton btnAddRow = new JButton(new AbstractAction("Add Row") {

            @Override
            public void actionPerformed(ActionEvent e) {
                tableModel.addRow(new Object[]{"new row"});
                int last = table.getModel().getRowCount() - 1;
                Rectangle r = table.getCellRect(last, 0, true);
                table.scrollRectToVisible(r);
            }
        });
        frame.add(scrollPane);
        frame.add(btnAddRow);
        frame.pack();
    }
}