Java8为LocalDateTime添加时间不起作用

问题描述

我尝试过如下，但在两种情况下它都显示同一时间？我做错了。

I tried like below, but in both the cases it is showing same time? What i am doing wrong.

    LocalDateTime currentTime = LocalDateTime.now(ZoneId.of("UTC"));
    Instant instant = currentTime.toInstant(ZoneOffset.UTC);
    Date currentDate = Date.from(instant);
    System.out.println("Current Date = " + currentDate);
    currentTime.plusHours(12);
    Instant instant2 = currentTime.toInstant(ZoneOffset.UTC);
    Date expiryDate = Date.from(instant2);
    System.out.println("After 12 Hours = " + expiryDate);

当前日期时间与12小时后相同......

"Current Date" Time is showing Same as "After 12 Hours"...

推荐答案

LocalDateTime 的文档指定 LocalDateTime 是不可变的，例如

The documentation of LocalDateTime specifies the instance of LocalDateTime is immutable, for example plusHours

返回指定的 LocalDateTime 的副本已添加
小时数。

Returns a copy of this LocalDateTime with the specified number of hours added.

此实例不可变且不受此方法调用的影响。

This instance is immutable and unaffected by this method call.

参数：

小时 - 要添加的小时数，可能为负数

退货：

a LocalDateTime基于此日期时间添加小时数，而不是null

投掷：

DateTimeException - 如果结果超出支持的日期范围

Parameters:
hours - the hours to add, may be negative
Returns:
a LocalDateTime based on this date-time with the hours added, not null
Throws:
DateTimeException - if the result exceeds the supported date range

那么，你创建一个新的 LocalDateTime实例执行加号操作时，需要按如下方式赋值：

So, you create a new instance of LocalDateTime when you execute plus operation, you need to assign this value as follows:

LocalDateTime nextTime = currentTime.plusHours(12);
Instant instant2 = nextTime.toInstant(ZoneOffset.UTC);
Date expiryDate = Date.from(instant2);
System.out.println("After 12 Hours = " + expiryDate);

我希望它对您有所帮助。

I hope it can be helpful for you.

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