从用户提供的时间中减去 45 分钟

Question

我正在尝试输入格式为 HH:mm（24 小时格式）的字符串，然后从给定时间减去 45 分钟以为用户提供新时间。这是我到目前为止完成的代码，但我一直收到不完整的类型错误。我是否错误地使用了 minusMinutes()？

编辑添加错误信息： “发现不兼容的类型：'java.time.LocalDateTime'，需要：'java.lang.String'：52'

public static boolean validateTime(String timeStr)
    {
        //Regular expression logic to validate correct format:
        // ( = start of group, [01]?[0-9] time can start with 0-9,1-9, 00-09,10-19
        // | = or, 2[0-5] represents start time with 20-23, ) = end group
        //
        String regex = "([01]?[0-9]|2[0-3]):[0-5][0-9]";
        Pattern p = Pattern.compile(regex);

        //if time empty return false
        if (timeStr == null)
        {
            return false;
        }

        //matcher method attempts to find match between given time and regex
        Matcher m = p.matcher(timeStr);
        //if given time and Regular expression matches,return true.
        return m.matches();

    }

    public static void main(String[] args) {

        Scanner myScanner = new Scanner(System.in);
        System.out.println("Enter time in 24 hr format (HH:mm): ");

        String timeIn = myScanner.nextLine(); // read user input
        while(!(validateTime(timeIn)))
        {
            System.out.println("Please enter valid time: ");
            timeIn = myScanner.nextLine();
        }

        System.out.println("Current Time is: " + timeIn);
        //String[] arrOfStr = timeIn.split("\:");

        DateTimeFormatter formatter = DateTimeFormatter.ofPattern("HH:mm");
        LocalDateTime datetime = LocalDateTime.parse(timeIn,formatter);
        String updatedTime = datetime.minusMinutes(45);
        System.out.println("New time to wake up: " + updatedTime);

Answer 1

您需要添加一个toString()来将时间对象字符串化。此外，由于您只阅读一次，因此请使用 LocalTime 而不是 LocalDateTime 您的最后几行将如下所示：

    DateTimeFormatter formatter = DateTimeFormatter.ofPattern("HH:mm");
    LocalTime datetime = LocalTime.parse(timeIn, formatter);
    String updatedTime = datetime.minusMinutes(45).toString();
    System.out.println("New time to wake up: " + updatedTime);

从用户提供的时间中减去 45 分钟

Subtract 45 minutes from time that user provided

java

string

time

date