开始日期和结束日期的校验弹窗代码java怎么写

以下是一个简单的日期校验弹窗代码示例，使用了JavaFX框架：

import java.time.LocalDate;
import javafx.application.Application;
import javafx.event.ActionEvent;
import javafx.geometry.Insets;
import javafx.scene.Scene;
import javafx.scene.control.Alert;
import javafx.scene.control.Button;
import javafx.scene.control.DatePicker;
import javafx.scene.layout.GridPane;
import javafx.stage.Stage;

public class DateChecker extends Application {

    @Override
    public void start(Stage primaryStage) {
        GridPane grid = new GridPane();
        grid.setPadding(new Insets(10, 10, 10, 10));
        grid.setVgap(5);
        grid.setHgap(5);

        DatePicker startDatePicker = new DatePicker();
        startDatePicker.setPromptText("Start Date");
        GridPane.setConstraints(startDatePicker, 0, 0);
        grid.getChildren().add(startDatePicker);

        DatePicker endDatePicker = new DatePicker();
        endDatePicker.setPromptText("End Date");
        GridPane.setConstraints(endDatePicker, 0, 1);
        grid.getChildren().add(endDatePicker);

        Button checkButton = new Button("Check Dates");
        GridPane.setConstraints(checkButton, 1, 0);
        grid.getChildren().add(checkButton);

        checkButton.setOnAction((ActionEvent e) -> {
            LocalDate startDate = startDatePicker.getValue();
            LocalDate endDate = endDatePicker.getValue();

            if (startDate == null || endDate == null) {
                Alert alert = new Alert(Alert.AlertType.WARNING);
                alert.setTitle("Date Checker");
                alert.setHeaderText(null);
                alert.setContentText("Please select both start and end dates.");
                alert.showAndWait();
            } else if (startDate.isAfter(endDate)) {
                Alert alert = new Alert(Alert.AlertType.ERROR);
                alert.setTitle("Date Checker");
                alert.setHeaderText(null);
                alert.setContentText("Start date cannot be after end date.");
                alert.showAndWait();
            } else {
                Alert alert = new Alert(Alert.AlertType.INFORMATION);
                alert.setTitle("Date Checker");
                alert.setHeaderText(null);
                alert.setContentText("Start date: " + startDate.toString() + "\nEnd date: " + endDate.toString());
                alert.showAndWait();
            }
        });

        Scene scene = new Scene(grid, 300, 150);
        primaryStage.setTitle("Date Checker");
        primaryStage.setScene(scene);
        primaryStage.show();
    }

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

该代码创建了一个简单的JavaFX应用程序，用户可以选择开始日期和结束日期，然后单击“Check Dates”按钮来检查这些日期。 如果开始日期晚于结束日期，将会弹出错误警告框，否则将会弹出信息框显示所选日期。