允许用户在 DatePicker 中仅选择星期一

Question

我正在处理一个 javafx 项目，并且我已经包含了一个 DatePicker。我想让用户只能选择星期一

DatePicker startDate = new DatePicker();

如果可能的话，有什么想法吗？

Answer 1

你需要做两件事：

1. 如果用户将文本字段中的日期更改为非星期一的日期，则否决更改。您可以使用 converter property 的 DatePicker 来做到这一点。
2. 禁用弹出窗口中非星期一的所有单元格。您可以使用dayCellFactory 来完成此操作。

简单示例：

import java.time.DayOfWeek;
import java.time.LocalDate;

import javafx.application.Application;
import javafx.geometry.Insets;
import javafx.scene.Scene;
import javafx.scene.control.DateCell;
import javafx.scene.control.DatePicker;
import javafx.scene.layout.StackPane;
import javafx.stage.Stage;
import javafx.util.Callback;
import javafx.util.StringConverter;

public class DatePickerMondaysOnly extends Application {

    @Override
    public void start(Stage primaryStage) {

        DatePicker datePicker = new DatePicker();

        StringConverter<LocalDate> defaultConverter = datePicker.getConverter();

        datePicker.setConverter(new StringConverter<LocalDate>() {

            @Override
            public String toString(LocalDate object) {
                return defaultConverter.toString(object);
            }

            @Override
            public LocalDate fromString(String string) {
                LocalDate date = defaultConverter.fromString(string);
                if (date.getDayOfWeek() == DayOfWeek.MONDAY) {
                    return date ;
                } else {
                    // not a Monday. Revert to previous value.
                    // You could also, e.g., return the closest Monday here.
                    return datePicker.getValue();
                }
            }

        });

        datePicker.setDayCellFactory(dp -> new DateCell() {
            @Override
            public void updateItem(LocalDate item, boolean empty) {
                super.updateItem(item, empty);
                setDisable(empty || item.getDayOfWeek() != DayOfWeek.MONDAY);               
            }
        });

        // Just for debugging: make sure we only see Mondays:
        datePicker.valueProperty().addListener((obs, oldDate, newDate) -> {
            if (newDate.getDayOfWeek() != DayOfWeek.MONDAY) {
                System.out.println("WARNING: date chosen was not a Monday");
            }
            System.out.println(newDate + " (" + newDate.getDayOfWeek()+")");
        });

        StackPane root = new StackPane(datePicker);
        root.setPadding(new Insets(20));
        primaryStage.setScene(new Scene(root));
        primaryStage.show();
    }

    public static void main(String[] args) {
        launch(args);
    }
}