Eng.Fouad Eng.Fouad - 1 month ago 5
Java Question

How to get BooleanBinding from comparing 2 DatePickers?

I have two

DatePicker
s and one
Button
on the GUI. I need to disable the button whenever the first datePicker has a date that is NOT before the second datePicker's date. i.e.
before
is
false
in the following snippet:

LocalDate date1 = dpFromDate.getValue();
LocalDate date2 = dpToDate.getValue();
boolean before = date1.isBefore(date2);
button.setDisable(!before);


using Bindings APIs.

BooleanBinding bb = ???;
button.disableProperty().bind(bb);





Here is my working solution, but I believe there is a better API to handle such situation:

BooleanBinding bb = Bindings.selectInteger(dpFromDate.valueProperty(), "year")
.greaterThanOrEqualTo(Bindings.selectInteger(dpToDate.valueProperty(), "year"));

bb = bb.or(
Bindings.selectInteger(dpFromDate.valueProperty(), "year")
.isEqualTo(Bindings.selectInteger(dpToDate.valueProperty(), "year"))
.and(Bindings.selectInteger(dpFromDate.valueProperty(), "monthValue")
.greaterThanOrEqualTo(Bindings.selectInteger(dpToDate.valueProperty(), "monthValue")))
);

bb = bb.or(
Bindings.selectInteger(dpFromDate.valueProperty(), "year")
.isEqualTo(Bindings.selectInteger(dpToDate.valueProperty(), "year"))
.and(Bindings.selectInteger(dpFromDate.valueProperty(), "monthValue")
.isEqualTo(Bindings.selectInteger(dpToDate.valueProperty(), "monthValue")))
.and(Bindings.selectInteger(dpFromDate.valueProperty(), "dayOfMonth")
.greaterThanOrEqualTo(Bindings.selectInteger(dpToDate.valueProperty(), "dayOfMonth")))
);

Answer

Just create a BooleanBinding depending on the DatePicker values that compares both dates. This way you don't have to write the functionality yourself and even more important - you don't need to create such a complicated binding:

BooleanBinding bb = Bindings.createBooleanBinding(() -> {
    LocalDate from = dpFromDate.getValue();
    LocalDate to = dpToDate.getValue();

    // disable, if one selection is missing or from is not smaller than to
    return (from == null || to == null || (from.compareTo(to) >= 0));
}, dpFromDate.valueProperty(), dpToDate.valueProperty());

button.disableProperty().bind(bb);
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