java - How to get BooleanBinding from comparing 2 DatePickers?

Question

I have two DatePickers 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 1

BooleanBinding只需根据DatePicker比较两个日期的值创建一个。这样您就不必自己编写功能，更重要的是 - 您不需要创建如此复杂的绑定：

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);