摘要：
错误：不支持字段：HourOfDay是一个有趣的低级错误。代码如下：LocalDatenow=LocalDate。now（）；Stringyear=now.format（DateTimeFormatter.Pattern（“yyyy”））；Stringhour=now.format（DateTimeFormatter.Pattern（“MM-dd HH”））；
报错:Unsupported field: HourOfDay
这个错误就比较搞笑也比较低级了.
代码如下
LocalDate now = LocalDate.now();
String year = now.format(DateTimeFormatter.ofPattern("yyyy"));
String hour = now.format(DateTimeFormatter.ofPattern("MM-dd-HH"));
报错如下
Exception in thread "main" java.time.temporal.UnsupportedTemporalTypeException: Unsupported field: HourOfDay
at java.time.LocalDate.get0(LocalDate.java:680)
at java.time.LocalDate.getLong(LocalDate.java:659)
at java.time.format.DateTimePrintContext.getValue(DateTimePrintContext.java:298)
at java.time.format.DateTimeFormatterBuilder$NumberPrinterParser.format(DateTimeFormatterBuilder.java:2540)
at java.time.format.DateTimeFormatterBuilder$CompositePrinterParser.format(DateTimeFormatterBuilder.java:2179)
at java.time.format.DateTimeFormatter.formatTo(DateTimeFormatter.java:1746)
at java.time.format.DateTimeFormatter.format(DateTimeFormatter.java:1720)
at java.time.LocalDate.format(LocalDate.java:1691)
at com.feiyangshop.recommendation.HdfsHandler.main(HdfsHandler.java:21)
我还追踪到了jdk源码中查看.
private int get0(TemporalField field) {
switch ((ChronoField) field) {
case DAY_OF_WEEK: return getDayOfWeek().getValue();
case ALIGNED_DAY_OF_WEEK_IN_MONTH: return ((day - 1) % 7) + 1;
case ALIGNED_DAY_OF_WEEK_IN_YEAR: return ((getDayOfYear() - 1) % 7) + 1;
case DAY_OF_MONTH: return day;
case DAY_OF_YEAR: return getDayOfYear();
case EPOCH_DAY: throw new UnsupportedTemporalTypeException("Invalid field 'EpochDay' for get() method, use getLong() instead");
case ALIGNED_WEEK_OF_MONTH: return ((day - 1) / 7) + 1;
case ALIGNED_WEEK_OF_YEAR: return ((getDayOfYear() - 1) / 7) + 1;
case MONTH_OF_YEAR: return month;
case PROLEPTIC_MONTH: throw new UnsupportedTemporalTypeException("Invalid field 'ProlepticMonth' for get() method, use getLong() instead");
case YEAR_OF_ERA: return (year >= 1 ? year : 1 - year);
case YEAR: return year;
case ERA: return (year >= 1 ? 1 : 0);
}
throw new UnsupportedTemporalTypeException("Unsupported field: " + field);
}
最后把异常抛出的代码在这.
说明我在now.format(DateTimeFormatter.ofPattern("MM-dd-HH"));的HH是不在case之中的.
为什么case中只有年月日,没有小时和分秒呢?
emmmmm.
答案就是:我用错类了
应该使用LocalDateTime这个类.这个类包含时分秒.
LocalDateTime now = LocalDateTime.now();
String year = now.format(DateTimeFormatter.ofPattern("yyyy"));
String hour = now.format(DateTimeFormatter.ofPattern("MM-dd-HH"));