不接受裸日期值作为DateTime。使用LocalDate而不是LocalDateTime解决问题：

  DateTimeFormatter formatter = DateTimeFormatter.ofPattern（yyyyMMdd）; 
 LocalDate dt = LocalDate.parse（20140218，格式化程序）; 
 

I am simply trying to convert a date string into a DateTime object in Java 8. Upon running the following lines:

DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyyMMdd");
LocalDateTime dt = LocalDateTime.parse("20140218", formatter);

I get the following error:

Exception in thread "main" java.time.format.DateTimeParseException: 
Text '20140218' could not be parsed: 
Unable to obtain LocalDateTime from TemporalAccessor: 
{},ISO resolved to 2014-02-18 of type java.time.format.Parsed
    at java.time.format.DateTimeFormatter.createError(DateTimeFormatter.java:1918)
    at java.time.format.DateTimeFormatter.parse(DateTimeFormatter.java:1853)
    at java.time.LocalDateTime.parse(LocalDateTime.java:492)

The syntax is identical to what has been suggested here, yet I am served with an exception. I am using JDK-8u25.

It turns out Java does not accept a bare Date value as DateTime. Using LocalDate instead of LocalDateTime solves the issue:

DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyyMMdd");
LocalDate dt = LocalDate.parse("20140218", formatter);