CODEWITHSUNDEEP
javafxmodel-binding
Molitoris
Molitoris

Reputation: 1035

How to call method for bind property

I know how to bind a property, but how can I bind the call of a fuction?

For example: I have a ObjectProperty which points to a file. Now, I want to bind the path to its folder? If the value of ObjectProperty is C:\\user\Desktop\text.txt, the bonding should point to C:\\user\Desktop.

I thought I can call getParentFile() within the binding.

Upvotes: 3

Views: 1460

Answers (1)

user8097737
user8097737

Reputation:

There a many ways to map an ObjectProperty, take a look at the class Bindings.

(All examples assume that you have a ObjectProperty<File> file)

  1. Bindings.createObjectBinding(Callable<T> func, Observable... dependencies)

    ObjectBinding<File> parent = Bindings.createObjectBinding(() -> {
    File f = file.getValue();
    return f == null ? null : f.getParentFile();
}, file);

  2. Bindings.select(ObservableValue<?> root, String... steps)

    ObjectBinding<File> parent = Bindings.select(file, "parentFile");

    This will print a warning on the error-stream when file is null.

You can also create your own mapping method (which is similar to createObjectBinding):

public static <T,R> ObjectBinding<R> map(ObjectProperty<T> property, Function<T,R> function) {
    return new ObjectBinding<R>() {
        {
            bind(property);
        }
        @Override
        protected R computeValue() {
            return function.apply(property.getValue());
        }
        @Override
        public void dispose() {
            unbind(property);
        }
    };
}

And use it

ObjectBinding<File> parent = map(file, f -> f == null ? null : f.getParentFile());

Upvotes: 5

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