Here is the question at stackoverflow if you want to respond there.
http://stackoverflow.com/questions/5212338/why-does-this-code-have-a-one-off-error
I am building a GWT component to behave much like the comments box
here on stackoverflow, and other sites. I am trying to register
listeners for KeyPress, Change and ONPASTE events that will update my
status line with number of characters remaining, etc.
It works except it is always one character behind the actual number of
characters in the text area. I set the max number of characters to 10.
When I type the first character it still says, "10 characters
remaining". It doesn't update the status line until I type the second
character and then it is one off, it says 9 characters remaining when
the second character is typed.
When I BACKSPACE or DELETE, it is also one off, when there are no
characters it still says "9 characters remaining" until I press the
BACKSPACE or DELETE a second time.
I am getting this behavior in both Firefox, Chrome and Internet
Explorer on Windows. So I think I am not registering something
correctly.
I know this has something to do with when the events are getting
fired, but I have spend hours on trying to diagnose this behavior and
have run out of ideas.
Here is where I am registering the event handlers, the complete code
is BoundedTextAreaWithFeedback.
private void registerHandlers()
{
final BoundedTextAreaWithFeedback outer = this;
this.textArea.addChangeHandler(new ChangeHandler()
{
public void onChange(final ChangeEvent changeEvent)
{
outer.validate();
}
});
this.textArea.addKeyPressHandler(new KeyPressHandler()
{
public void onKeyPress(final KeyPressEvent keyPressEvent)
{
outer.validate();
}
});
this.panel.addFocusHandler(new FocusHandler()
{
public void onFocus(final FocusEvent focusEvent)
{
outer.textArea.setFocus(true);
}
});
// capture paste events
this.textArea.sinkEvents(Event.ONPASTE);
}
Here is the validate() method.
private boolean validate()
{
final boolean isValid;
final int len = this.textArea.getText().length();
if (len < this.minLength)
{
this.status.setText("Enter at least " + this.minLength + "
characters.");
this.status.setStyleName("input-status-underflow");
isValid = false;
}
else if (len > this.maxLength)
{
this.status.setText(this.maxLength - len + " characters
remaining");
this.status.setStyleName("input-status-overflow");
isValid = false;
}
else
{
this.status.setText(this.maxLength - len + " characters
remaining");
this.status.setStyleName("input-status-ok");
isValid = true;
}
return isValid;
}
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