Encountered some problems with JTextField. Perhaps someone can identify either
my confusion or a workaround... It would also be interesting to know
if the same
things happen on other platforms.
(1) If I edit the text in a JTextField, revalidate is called
(correctly, I believe, as the
preferred size tracks the current text), but for some reason the layout is not
updated. In my test code, getPreferredSize() is not called.
(2) If I insert a character when the caret is at the right edge of
the field, several
things go wrong. (A) If the caret is set to blink, it stops blinking.
(B) The focus ring
is overwritten. (C) The JTextField is repainted continuously at a
high rate. This
repainting is not the caret blink repainting, as it happens even if
the caret is set
to not blink. This problem might be related to a JTextField performance problem
that was reported in Oct 2004 but not confirmed by others.
I have observed these problems in the latest 1.4.2 and the latest DP of 1.5
and with both the Aqua and Metal L&Fs.
If you type a character while the carat is at the right edge
of the field,
paint will be called repeatedly and apparently forever at a fast rate,
faster than the blink rate, regardless of whether
the caret is set to blink or not. If the caret is set to
blink, it stops
blinking. Deleting the character will restore normal behavior, as will
resizing the window. It also appears
that the focus ring is being overwritten on the right side of the field
when this happens.
Although revalidate is called when the user edits the text, the layout
is not redone until the window is resized.
Using the Metal look and feel does not solve the problems.
Observed in latest 1.4.2 and 1.5 DP.
*/
public class TestJTextField
{
public static void main(String[] args)
{
System.out.println("Version: " +
System.getProperty("java.version"));
boolean blink = (args.length > 0 && args[0].equals("b"));
new TestJTextField(blink);
}
public TestJTextField(boolean blink)
{
fr = new JFrame();
f = new MyJTextField("Horse", blink);
f.setEditable(true);
fr.getContentPane().add(f);
GridBagLayout l = new GridBagLayout();
GridBagConstraints c = new GridBagConstraints();
c.gridx = 0;
c.gridy = 0;
c.fill = GridBagConstraints.NONE;
l.setConstraints(f, c);
fr.getContentPane().setLayout(l);
fr.setSize(300, 100);
fr.setVisible(true);
}
private class MyJTextField
extends JTextField
{
public MyJTextField(String s, boolean blink)
{
super(s);
if (!blink) {
Caret c = getCaret();
c.setBlinkRate(0);
}
}
public void revalidate()
{
if (debugFlag) System.out.println("revalidate");
super.revalidate();
}
public void repaint()
{
if (debugFlag) System.out.println("repaint");
super.repaint();
}
public void paint(Graphics g)
{
if (debugFlag) System.out.println("paint " +
(++counter));
super.paint(g);
}
public Dimension getPreferredSize()
{
if (debugFlag) System.out.println("getPreferredSize");
return super.getPreferredSize();
}
public void setBounds(int x, int y, int w, int h)
{
if (debugFlag) System.out.println("setBounds");
super.setBounds(x, y, w, h);
}
}
}
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