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From: Knute Johnson <eternal@knutejohnson.com>
Newsgroups: comp.lang.java.programmer
Subject: Re: Problem with JavaFX ChangeListener?
Date: Thu, 11 Dec 2014 18:31:21 -0800
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On 12/11/2014 18:24, Arne Vajhøj wrote:
> On 12/11/2014 6:08 PM, Knute Johnson wrote:
>> The other question I have is why does the ObservableValue require a cast
>> to StringProperty in both of the working examples and why do I declare
>> it as <? extends String>?
>>          class LengthListener<String> implements ChangeListener<String> {
>>              private final int length;
>>
>>              public LengthListener(int length) {
>>                  this.length = length;
>>              }
>>
>>              @Override public void changed(
>>               ObservableValue<? extends String> observable,
>>               String oldValue,String newValue) {
>>                  if (newValue.length() > length)
>>                      ((StringProperty)observable).setValue(
>>                       newValue.substring(0,length));
>>              }
>>          }
>>          textField.textProperty().addListener(new LengthListener(4));
>
> Formal type of observable:
>
> interface javafx.beans.value.ObservableValue
>
> Actual ype of observable:
>
> class javafx.scene.control.TextInputControl$TextProperty
> **** class javafx.beans.property.StringProperty
> ******** interface javafx.beans.value.ObservableValue
>
> The cast is necessary!
>
> Arne

OK, I see now.  Thanks for that too Arne.

-- 

Knute Johnson