java - 如何通过比较2个DatePickers获得BooleanBinding？

我在GUI上有两个DatePicker和一个Button。每当第一个datePicker的日期不早于第二个datePicker的日期时，就需要禁用该按钮。即以下代码段中的before是false：

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

使用Bindings API。

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

这是我的工作解决方案，但我相信有一个更好的API可以处理这种情况：

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")))
   );

最佳答案

只需根据比较两个日期的BooleanBinding值创建一个DatePicker。这样，您不必自己编写功能，甚至更重要的是-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);