Restrict input type on a JTextField

[Bravogolf]

Hi all,
I have a textfield with an actionlistener that performs a mathematical calculation, so it will only take number.
If it type in text and press enter, it displays various errors in the compiler (naturally).

How can I insert in the action listener that if the value of the textfield is text then do nothing?

 

[stefanwagner]

'Number' isn't a very clear term in the Java-field.
Here I got some expressions, which might be a number in some context:

1
-1
-1.
-1,
0xe7
0.333
0,333
,3
.3
7e-24
IX 
O777
101101010(2)
9a7fgz

Sometimes this will work:

String s = tf.getText ();
int i = 0;
try
{
   i = Integer.parseInt (s);
}
catch (NumberFormatException nfe)
{
   // Messagebox: please try again...
}

For non-ints there are similar methods.

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[Bravogolf]

Thanks, stefanwagner. That did the job