JTextField / JTextComponent中的选择有限? [英] Limited selection in a JTextField/JTextComponent?
问题描述
考虑一个JFormattedTextField(或任何真正的JTextComponent),其中有一个前缀和一个后缀显示在该字段的实际文本周围。
Consider a JFormattedTextField (or any JTextComponent, really) wherein there is a prefix and a suffix displayed around what is the actual "text" of the field.
For例如,double 3.5将是字符串(通过格式化)3.50,其前面是前缀$和后缀,显示文本为$ 3.50。
For instance, the double 3.5 would be the String (via formatting) "3.50" around which would be the prefix "$ " and the suffix "", for a display text of "$ 3.50".
显然,这很容易做到。但是,仍然允许用户选择前缀/后缀中的文本,因此可以想象删除部分或全部前缀/后缀。我希望限制用户,使得根本不能选择前缀/后缀(仍然是文本字段的一部分,因此没有JLabel)。我几乎可以使用CaretListener(或重写setCaretPosition / moveCaretPosition)来完成此操作,这会阻止C-a选择整个字段,并且它会阻止使用箭头键移动到前缀/后缀中。但是,鼠标拖动和移动箭头键仍然允许选择移动到这些限制区域。
Clearly, this is simple to do. However, the user is still allowed to select text within the prefix/suffix, so they could conceivably delete part or all of the prefix/suffix. I would prefer the user be restricted such that the prefix/suffix cannot be selected at all (while still part of the text field, so no JLabels). I can almost accomplish this with a CaretListener (or by overriding setCaretPosition/moveCaretPosition), which prevents a C-a from selecting the entire field, and it prevents using the arrow keys to move into the prefix/suffix. However, mouse dragging and shift-arrow keys still allows the selection to move into these restricted areas.
任何想法?
推荐答案
你可以使用NavigationFilter。
You can use a NavigationFilter for this.
这是一个让你入门的例子:
Here is an example to get you started:
import java.awt.event.*;
import javax.swing.*;
import javax.swing.text.*;
public class NavigationFilterPrefixWithBackspace extends NavigationFilter
{
private int prefixLength;
private Action deletePrevious;
public NavigationFilterPrefixWithBackspace(int prefixLength, JTextComponent component)
{
this.prefixLength = prefixLength;
deletePrevious = component.getActionMap().get("delete-previous");
component.getActionMap().put("delete-previous", new BackspaceAction());
component.setCaretPosition(prefixLength);
}
public void setDot(NavigationFilter.FilterBypass fb, int dot, Position.Bias bias)
{
fb.setDot(Math.max(dot, prefixLength), bias);
}
public void moveDot(NavigationFilter.FilterBypass fb, int dot, Position.Bias bias)
{
fb.moveDot(Math.max(dot, prefixLength), bias);
}
class BackspaceAction extends AbstractAction
{
public void actionPerformed(ActionEvent e)
{
JTextComponent component = (JTextComponent)e.getSource();
if (component.getCaretPosition() > prefixLength)
{
deletePrevious.actionPerformed( null );
}
}
}
public static void main(String args[]) throws Exception {
JTextField textField = new JTextField("Prefix_", 20);
textField.setNavigationFilter( new NavigationFilterPrefixWithBackspace(7, textField) );
JFrame frame = new JFrame("Navigation Filter Example");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(textField);
frame.pack();
frame.setLocationRelativeTo( null );
frame.setVisible(true);
}
}
我相信这是JFormattedTextField的工作原理。因此,我不确定您是否可以将其与格式化文本字段一起使用,因为它可能会替换默认行为。
I believe this is a how a JFormattedTextField works. So I'm not sure if you can use this with a formatted text field as is may replace the default behaviour.
这篇关于JTextField / JTextComponent中的选择有限?的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持IT屋!