Replace Text with number in TextField - javafx-2

Question

I have this field in which I insert port number. I would like to convert the string automatically into number:
fieldNport = new TextField();
fieldNport.setPrefSize(180, 24);
fieldNport.setFont(Font.font("Tahoma", 11));
grid.add(fieldNport, 1, 1);
Can you tell how I can do this? I cannot find suitable example in stack overflow.
EDIT:
Maybe this:
fieldNport.textProperty().addListener(new ChangeListener()
{
#Override
public void changed(ObservableValue o, Object oldVal, Object newVal)
{
try
{
int Nport = Integer.parseInt((String) oldVal);
}
catch (NumberFormatException e)
{
}
}
});

Answer 1

Starting with JavaFX 8u40, you can set a TextFormatter object on a text field:
UnaryOperator<Change> filter = change -> {
String text = change.getText();
if (text.matches("[0-9]*")) {
return change;
}
return null;
};
TextFormatter<String> textFormatter = new TextFormatter<>(filter);
fieldNport = new TextField();
fieldNport.setTextFormatter(textFormatter);
This avoids both subclassing and duplicate change events that you will get when you add a change listener to the text property and modify the text in that listener.

Answer 2

You can write something like this :
fieldNPort.text.addListener(new ChangeListener(){
#Override public void changed(ObservableValue o,Object oldVal, Object newVal){
//Some Code
//Here you can use Integer.parseInt methods inside a try/catch
//because parseInt throws Exceptions
}
});
Here are all the things you'd need about properties and Listeners in JavaFX:
http://docs.oracle.com/javafx/2/binding/jfxpub-binding.htm
If you have any question, I'll be glad to help.

Answer 3

Maybe this is what you need:
fieldNPort= new TextField()
{
#Override
public void replaceText(int start, int end, String text)
{
if (text.matches("[0-9]*"))
{
super.replaceText(start, end, text);
}
}
#Override
public void replaceSelection(String text)
{
if (text.matches("[0-9]*"))
{
super.replaceSelection(text);
}
}
};
This will restrict the users from entering anything but numbers(you can modify the regex expression to your needs) and then you do not have to worry about Integer.parseInt throwing any exception.