如何在 Java 中將 Sting 轉換為 ZonedDateTime

Question

我的輸入字符串沒有區域：

String formatter = "yyyy-MM-dd";
String zone = "Europe/London";
String date = ZonedDateTime.now(ZoneId.of(zone)).format( DateTimeFormatter.ofPattern(formatter));
System.out.println("date: " + date);
// 
ZonedDateTime dateTime = ZonedDateTime.parse(date , DateTimeFormatter.ofPattern(formatter).withZone(ZoneId.systemDefault()));
String after = dateTime.plusDays(1).format( DateTimeFormatter.ofPattern(formatter));
System.out.println("after: " + after);

我的控制台打印了第一個 syso，但出現此錯誤后：

date: 2019-12-17
Exception in thread "main" java.time.format.DateTimeParseException: Text '2019-12-17' could not be parsed: Unable to obtain ZonedDateTime from TemporalAccessor: {},ISO,Europe/Paris resolved to 2019-12-17 of type java.time.format.Parsed
    at java.time.format.DateTimeFormatter.createError(DateTimeFormatter.java:1920)
    at java.time.format.DateTimeFormatter.parse(DateTimeFormatter.java:1855)
    at java.time.ZonedDateTime.parse(ZonedDateTime.java:597)
    at com.id2s.application.business.service.impl.Sof.main(Sof.java:16)
Caused by: java.time.DateTimeException: Unable to obtain ZonedDateTime from TemporalAccessor: {},ISO,Europe/Paris resolved to 2019-12-17 of type java.time.format.Parsed
    at java.time.ZonedDateTime.from(ZonedDateTime.java:565)
    at java.time.format.Parsed.query(Parsed.java:226)
    at java.time.format.DateTimeFormatter.parse(DateTimeFormatter.java:1851)

預計在plusDays(1) ： 2019-12-18

Answer 1

ZonedDateTime是一個知道區域、日期和時間的對象。 您尚未提供有關時間的任何信息，因此可以將String解析為僅知道日期的對象。

但是，您可以使用一天的開始來從解析的LocalDate創建一個ZonedDateTime ，如下所示：

public static void main(String[] args) {
    String formatter = "yyyy-MM-dd";
    String zone = "Europe/London";
    String date = ZonedDateTime.now(ZoneId.of(zone))
            .format(DateTimeFormatter.ofPattern(formatter));
    System.out.println("date: " + date);
    // create a LocalDate first
    LocalDate localDate = LocalDate.parse(date);
    // then use that and the start of that day (00:00:00) in order to parse a ZonedDateTime
    ZonedDateTime dateTime = localDate.atStartOfDay(ZoneId.systemDefault()); 

    String after = dateTime.plusDays(1).format(DateTimeFormatter.ofPattern(formatter));
    System.out.println("after: " + after);
}

哪個輸出

date: 2019-12-17
after: 2019-12-18