仅在适合视口的情况下启用JTable的自动调整大小
问题内容:
我需要在JScrollPane内用可调整大小的列创建一个JTable(当用户增加列宽-
出现水平滚动条时)。为此我有用table.setAutoResizeMode(JTable.AUTO_RESIZE_OFF);
。同样,当视口足够宽以容纳整个表格时,列应拉伸以填充视口宽度。为此,我具有getScrollableTracksViewportWidth()
JTable类的重写方法,如下所示:
@Override
public boolean getScrollableTracksViewportWidth() {
return getPreferredSize().width < getParent().getWidth();
}
这种方法行之有效,除了一件事:当我第一次尝试调整列的大小时,它将自己的宽度返回到开始位置。如果我快速调整列的大小并释放鼠标表,则可以继续正常工作。那么,这种行为的原因是什么呢?为什么表即使getScrollableTracksViewportWidth()
返回false
也会尝试调整大小?或者,也许可以为实现这种调整大小模式提出更好的解决方案?
贝娄是上述问题的简单工作示例:
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);
}
});
}
}
问题答案:
doLayout()
当您在水平滚动条不可见的情况下尝试增加列的大小时,默认逻辑似乎不起作用,因此我摆脱了默认逻辑,只接受了列的宽度,而没有尝试对其进行调整。
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);
}
});
}
}
编辑为使用AUTO_RESIZE_ALL_COLUMNS。