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Groups > comp.lang.java.programmer > #13417

Re: inputvalidation of inputdialog

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On 4/5/2012 5:48 AM, Mark Sudau wrote:
> I already thought of a KeyListener but using a KeyListener makes it
> difficult to validate the length of a regular expression.


A key listener is probably the wrong direction entirely.  For length, 
make a Document and set the text field's document to that, or use a 
document listener, or use a DocumentFilter.

Something like (untested):

   DocumentFilter filter = new DocumentFilter() {
      private final int MAX_LEN = 42;
      public void insertString( FilterBypass fb,
          int offset, String string, AttributeSet att )
      {
        if( fb.getDocument().getLength() + string.getLength()
                < MAX_LEN )
        {
          fb.insertString( offset, string, attr );
        }
      }
      public void replaceString( FilterBypass fb,
          int offset, String string, AttributeSet att )
      {
        fb.replaceString( offset, string, attr );
      }
    };


In general, use the validators that Java already provides, don't roll 
your own.

<http://docs.oracle.com/javase/tutorial/uiswing/misc/focus.html>

(You have to scroll down a bit to get to the part about validating 
input.  It's there though, honest.)


Other links:


<http://docs.oracle.com/javase/tutorial/uiswing/components/formattedtextfield.html>

<http://docs.oracle.com/javase/7/docs/api/javax/swing/InputVerifier.html>

<http://docs.oracle.com/javase/7/docs/api/javax/swing/text/DocumentFilter.html>

PlainDocument is an AbstractDocument that you could easily extend.  I 
think PlainDocument is the model used for all plain text fields in Swing 
as well as the unformatted (plain) text areas.

<http://docs.oracle.com/javase/7/docs/api/javax/swing/text/PlainDocument.html>

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inputvalidation of inputdialog Mark Sudau <news@sudau.net> - 2012-04-05 14:48 +0200
  Re: inputvalidation of inputdialog markspace <-@.> - 2012-04-05 09:31 -0700

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