从日期取星期几

Question

我的程序有问题，我必须在其中插入一个随机日期 (dd/MM/yyyy)，如果当天是星期五或星期六，它应该打印出“是聚会时间”。我插入星期五或星期六的日期，但它仍然打印出“你应该学习”。有人可以帮忙吗？

Scanner scanner = new Scanner(System.in);
    String input = scanner.nextLine();
    DateTimeFormatter formatter = DateTimeFormatter.ofPattern("dd/MM/yyyy");
    LocalDate date = LocalDate.parse(input, formatter);
    System.out.println(date.getDayOfWeek().name());

    if (date.getDayOfWeek().equals("FRIDAY")) {
        System.out.println("Time for party, because it is: " + date.getDayOfWeek());
    }
    else if (date.getDayOfWeek().equals("SATURDAY"))
        System.out.println("Time for party, because it is: " + date.getDayOfWeek());
    else {
        System.out.println("You should study! It is: " + date.getDayOfWeek());
    }

Answer 1

LocalDate.getDayOfWeek 返回DayOfWeek 类型的枚举。但是您正在将字符串与枚举进行比较。

你必须这样做

date.getDayOfWeek() == DayOfWeek.FRIDAY

Answer 2

您应该将字符串值替换为枚举类型 DayOfWeek.FRIDAY 或 DayOfWeek.SATURDAY。当您将字符串与枚举进行比较时。

if (date.getDayOfWeek().equals(DayOfWeek.FRIDAY)) {
                System.out.println("Time for party, because it is: " + date.getDayOfWeek());
            }
            else if (date.getDayOfWeek().equals(DayOfWeek.SATURDAY))
                System.out.println("Time for party, because it is: " + date.getDayOfWeek());
            else {
                System.out.println("You should study! It is: " + date.getDayOfWeek());
            }

Answer 3

您将DayOfWeek 实例与String 实例进行比较，因此它们永远不会相等，因为它们是不同的类型。

一种解决方案是在调用 equals 之前调用 toString：

if (date.getDayOfWeek().toString().equals("FRIDAY")){...}

或更好的使用：

if (date.getDayOfWeek() == DayOfWeek.FRIDAY) {...}