How to capture input of JTextField

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Nick H - 07 Feb 2004 21:23 GMT

Hello,
I want to be able to capture the input of a JTextField and do things
based on what key was pressed. Basically this is for a textfield that
will allow the user to type in a value in pence, and for the number to
come up in GBP in a "£x.yz" format. I've looked at Inputmap and
Actionmap and I can get them to do things when I pressed a certain
key... but it still enters the text into the box and I have to set it up
for each key. Is it possible to intercept the key presses and use them
before the textfield does?

Thanks

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Nick H

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ak - 07 Feb 2004 23:58 GMT

> I want to be able to capture the input of a JTextField and do things
> based on what key was pressed. Basically this is for a textfield that
[quoted text clipped - 4 lines]
> for each key. Is it possible to intercept the key presses and use them
> before the textfield does?

better you use Document to control input.

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hiwa - 08 Feb 2004 09:41 GMT

> Hello,
> I want to be able to capture the input of a JTextField and do things
[quoted text clipped - 7 lines]
>
> Thanks

KeyListener

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Nick H - 09 Feb 2004 18:39 GMT

>>Hello,
>> I want to be able to capture the input of a JTextField and do things
[quoted text clipped - 9 lines]
>
> KeyListener

Hi,
I just tried that but it still enters the keys typed into the box. I
want to be able to control the box.

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ak - 09 Feb 2004 22:44 GMT

> > KeyListener
>
> Hi,
> I just tried that but it still enters the keys typed into the box. I
> want to be able to control the box.

JTextField field = new JTextField(new MyDocument());

class MyDocument extends PlaintDocument {
public void insertString(int offset, String str, AttributeSet a) {
//check here your staff
if(<str is not ok>) {
return;
}
else {
super.insertString(offset, str, a);
}
}
}

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Nick H - 11 Feb 2004 10:06 GMT

>[code and stuff]

Thanks ak, I used some of yours and some stuff from the Sun website and
got it to work! Great stuff

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Nick H

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Nick Howes - 11 Feb 2004 10:57 GMT

>> [code and stuff]
>
> Thanks ak, I used some of yours and some stuff from the Sun website and
> got it to work! Great stuff

Hmm, maybe not...

I use the method to check that the input is a number key, and then add
that to an internal string. Then I want the box text to be set to
something else based on that (a currency-formatted string). The problem
is that insertString only appends text and I want it to replace the
existing text after every key-press.
So I tried using the super.replace() method, but I think that uses
insertString so it starts infinitely recursing til there's a stack
overflow.

Any ideas?

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Nick H

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ak - 11 Feb 2004 16:53 GMT

> I use the method to check that the input is a number key, and then add
> that to an internal string. Then I want the box text to be set to
[quoted text clipped - 4 lines]
> insertString so it starts infinitely recursing til there's a stack
> overflow.

you should use super.insertString().

may be you also coulduse JFormattedTextField.

--

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How to capture input of JTextField

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