Bidirectional bindings of different properties

Question

I just tried to bind a Integer and a String property. After some googling this should be possible with one of the two provided methods:

1. public static void bindBidirectional(Property stringProperty,
   Property otherProperty, StringConverter converter)

2. public static void bindBidirectional(Property stringProperty,
   Property otherProperty, java.text.Format format)

Unluckily this does not seem to work for me. What am I doing wrong?

import java.text.Format;

import javafx.beans.binding.Bindings;
import javafx.beans.property.SimpleIntegerProperty;
import javafx.beans.property.SimpleStringProperty;
import javafx.util.converter.IntegerStringConverter;

public class BiderectionalBinding {

    public static void main(String[] args) {
        SimpleIntegerProperty intProp = new SimpleIntegerProperty();
        SimpleStringProperty textProp = new SimpleStringProperty();

        Bindings.bindBidirectional(textProp, intProp, new IntegerStringConverter());

        intProp.set(2);
        System.out.println(textProp);

        textProp.set("8");
        System.out.println(intProp);    
    }
}

Osana

If your question has been resolved. You should accept an answer. – Debi

Is there a more generic answer to this question (or a more generic question, for that matter)? I'd like to bind two properties, one of which are not a String. – Atalaya

Answer 1

Simple matter of type confusion

Bindings.bindBidirectional(textProp, intProp, new IntegerStringConverter());

Should be:

Bindings.bindBidirectional(textProp, intProp, new NumberStringConverter());

Debi

Answer 2

I tried your code in Eclipse and had to cast the converter. Then everything looks ok:

public class BiderectionalBinding {

    public static void main(String[] args) {
        SimpleIntegerProperty intProp = new SimpleIntegerProperty();
        SimpleStringProperty textProp = new SimpleStringProperty();
        StringConverter<? extends Number> converter =  new IntegerStringConverter();

        Bindings.bindBidirectional(textProp, intProp,  (StringConverter<Number>)converter);

        intProp.set(2);
        System.out.println(textProp);

        textProp.set("8");
        System.out.println(intProp);    
    }
}

The output is:

StringProperty [value: 2]

IntegerProperty [value: 8]

Wellmannered

Perfect, thank you. I got also other helpful answers at forums.oracle.com/forums/message.jspa?messageID=10773242 – Osana

For more informations about the JavaFX Property API read docs.oracle.com/javafx/2/api/javafx/beans/binding/Bindings.html – Wellmannered

Answer 3

i had a similar problem. I tried to convert a string into a File-Object and back. But i used Bindings.bindBidirectional(...,...,java.text.Format). The conversion from the string to file worked as expected but in the other direction the result was null. I tried it with your example, same Result! I think there is a bug in the binding mechanism, or maybe my implementation of java.text.Format is wrong..

package de.ludwig.binding.model;

import java.text.FieldPosition;
import java.text.Format;
import java.text.ParsePosition;

import javafx.beans.binding.Bindings;
import javafx.beans.property.SimpleIntegerProperty;
import javafx.beans.property.SimpleStringProperty;

public class BidirectionalBinding {

    public static void main(String[] args) {
        SimpleIntegerProperty intProp = new SimpleIntegerProperty();
        SimpleStringProperty textProp = new SimpleStringProperty();

        Bindings.bindBidirectional(textProp, intProp, new Format() {

            @Override
            public StringBuffer format(Object obj, StringBuffer toAppendTo,
                    FieldPosition pos) {
                return toAppendTo.append(obj.toString());
            }

            @Override
            public Object parseObject(String source, ParsePosition pos) {
                return Integer.parseInt(source);
            }

        });

        intProp.set(2);
        System.out.println(textProp);

        textProp.set("8");
        System.out.println(intProp);    
    }
}

The only way to get things working as expected was to implement StringConverter as recommended by Hendrik Ebbers. Thank you for this tip!

Abdu

Why dont you add that part into your code so this answer become useful for others. Other wise this is not a good answer if some one is looking for that same issue. – Taunyataupe

Answer 4

I think that is a bug. Anyway you can workaround like:

StringConverter sc = new IntegerStringConverter();
Bindings.bindBidirectional(textProp, intProp, sc);

Natica

Do you mean it's a bug in Java, the OP's code, the OP's IDE, or elsewhere? – Flitting