仅当JTable适合视口时才启用JTable的自动调整大小 [英] Enabling auto resize of JTable only if it fit viewport

问题描述

我需要在JScrollPane中创建一个带有可调整大小的列的JTable（当用户增加列宽时 - 出现水平滚动条）。
为此，我使用 table.setAutoResizeMode（JTable.AUTO_RESIZE_OFF）; 。
此外，当视口宽度足以包含整个表格时 - 列应该拉伸以填充视口宽度。
为了实现这个目的，我覆盖了 getScrollableTracksViewportWidth（） JTable类的方法如下：

I need to create a JTable inside JScrollPane with resizeable columns (when user increase column width - horizontal scrollbar appears). For this I have use table.setAutoResizeMode(JTable.AUTO_RESIZE_OFF);. Also, when viewport is wide enough to contain entire table - columns should stretch to fill viewport width. To accomplish this I have override getScrollableTracksViewportWidth() method of JTable class as follow:

@Override
public boolean getScrollableTracksViewportWidth() {
    return getPreferredSize().width < getParent().getWidth();
}

这种方法效果很好，除了一件事：当我第一次尝试调整大小时列返回自己的宽度以开始位置。如果我快速调整列并释放鼠标表继续工作正常。
那么，这种行为的原因是什么？为什么表尝试调整大小，即使 getScrollableTracksViewportWidth（）返回false？或者，也许，你可以提出更好的解决方案来实现这样的调整大小模式吗？

This approach works good, except one thing: when I first time try to resize column it return own width to start position. If I quickly resize column and release mouse table continue to work good. So, what is the reason of such behavior? Why table try to resize even if getScrollableTracksViewportWidth() returns false? Or, maybe, you can propose better solution for implementing such resize mode?

Bellow是上述问题的简单工作示例：

Bellow is a simple working example of above problem:

import javax.swing.*;

public class TestTable {
    private static Object[][] data = new Object[][] {
            { "a", "b", "c" },
            { "d", "e", "f" }
    };
    private static Object[] colNames = new Object[] { "1", "2", "3" };

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                JTable table = new JTable(data, colNames) {
                    @Override
                    public boolean getScrollableTracksViewportWidth() {
                        return getPreferredSize().width < getParent().getWidth();
                    }
                };
                table.setAutoResizeMode(JTable.AUTO_RESIZE_OFF);

                JFrame frame = new JFrame();
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.add(new JScrollPane(table));
                frame.pack();
                frame.setVisible(true);
            }
        });
    }
}

推荐答案

它看起来像默认的 doLayout（）逻辑不起作用当你试图在水平滚动条不可见时增加列的大小，所以我摆脱了默认逻辑，只是接受了列的宽度，而没有尝试调整它。

It seemed like the default doLayout() logic wasn't working when you tried to increase the size of a column when the horizontal scrollbar wasn't visible, so I got rid of the default logic and just accepted the width of the column without attempting to adjust it.

import javax.swing.*;
import javax.swing.table.*;

public class TestTable {
    private static Object[][] data = new Object[][] {
            { "a", "b", "c" },
            { "d", "e", "f" }
    };
    private static Object[] colNames = new Object[] { "1", "2", "3" };

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                JTable table = new JTable(data, colNames)
                {
                    @Override
                    public boolean getScrollableTracksViewportWidth()
                    {
                        return getPreferredSize().width < getParent().getWidth();
                    }

                    @Override
                    public void doLayout()
                    {
                        TableColumn resizingColumn = null;

                        if (tableHeader != null)
                            resizingColumn = tableHeader.getResizingColumn();

                        //  Viewport size changed. May need to increase columns widths

                        if (resizingColumn == null)
                        {
                            setAutoResizeMode(JTable.AUTO_RESIZE_ALL_COLUMNS);
                            super.doLayout();
                        }

                        //  Specific column resized. Reset preferred widths

                        else
                        {
                            TableColumnModel tcm = getColumnModel();

                            for (int i = 0; i < tcm.getColumnCount(); i++)
                            {
                                TableColumn tc = tcm.getColumn(i);
                                tc.setPreferredWidth( tc.getWidth() );
                            }

                            // Columns don't fill the viewport, invoke default layout

                            if (tcm.getTotalColumnWidth() < getParent().getWidth())
                                setAutoResizeMode(JTable.AUTO_RESIZE_ALL_COLUMNS);
                                super.doLayout();
                        }

                        setAutoResizeMode(JTable.AUTO_RESIZE_OFF);
                    }

                };
                table.setAutoResizeMode(JTable.AUTO_RESIZE_OFF);

                JFrame frame = new JFrame();
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.add(new JScrollPane(table));
                frame.pack();
                frame.setVisible(true);
            }
        });
    }
}

编辑使用AUTO_RESIZE_ALL_COLUMNS。

Edited to use AUTO_RESIZE_ALL_COLUMNS.

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