“plusDays” doesn't advance LocalDate in Java 8

问题

Why is LocalDate not changing even though there is no error during running?

DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd");
LocalDate date = LocalDate.parse("2005-12-12", formatter);
date.plusDays(3);
System.out.println(date.toString());

Output:

2005-12-12

Anything I missed out?

回答1:

LocalDate is immutable

date = date.plusDays(3);

回答2:

As a String, it doesn't have an effect calling a method on it without assigning the result :

date = date.plusDays(3);

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来源：https://stackoverflow.com/questions/33333201/plusdays-doesnt-advance-localdate-in-java-8