Java如何把+0800改成+0000？

Question

如何在Java中将2018-12-24 12:00:00 +0800更改为2018-12-23 16:00:00 +0000？

private String currentDateandTime = new Date();

final DateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd", Locale.CHINA);
final DateFormat fullFormat = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss XX", Locale.CHINA);
//dateFormat.setTimeZone(TimeZone.getTimeZone("Asia/Shanghai"));
//fullFormat.setTimeZone(TimeZone.getTimeZone("Asia/Shanghai"));

Date dateTest = dateFormat.parse(currentDateandTime);
currentDateandTime = fullFormat.format(dateTest);

currentDateanTime 结果

2018-12-24 12:00:00 +0800

Answer 1

需要为全格式设置 "GMT" 时区 (+0000)，以便将默认时区转换为使用 GMT 时区：

Date currentDateandTime = new Date();

final DateFormat fullFormat = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss XX", Locale.CHINA);
TimeZone gmtTime = TimeZone.getTimeZone("GMT");
fullFormat.setTimeZone(gmtTime);
String currentDateandTimeInGMTFullFormat = fullFormat.format(currentDateandTime);

Answer 2

嗯，你的代码开始有问题。

private String currentDateandTime = new Date();

假设 Date() 是从这里导入的 java.util.Date

这一行应该显示编译器错误

无论如何，我假设您想将 LocalTimezone DateTime 转换为 GMT 日期时间

Date currentDate = new Date();
System.out.println(currentDate);

final DateFormat gmtFormatter = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss");
gmtFormatter.setTimeZone(TimeZone.getTimeZone("GMT"));
String convertedDate = gmtFormatter.format(currentDate);
System.out.println(convertedDate);

OUTPUT:
Mon Dec 24 09:52:14 IST 2018
2018-12-24 04:22:14

Answer 3

如果只想获取不同时区的同一个实例，可以这样：

DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss Z");
OffsetDateTime offsetDateTime = OffsetDateTime.parse("2018-12-24 12:00:00 +0800", formatter);
ZonedDateTime dateTimeInDesiredZoned = offsetDateTime.atZoneSameInstant(ZoneId.of("UTC"));
// 2018-12-24 04:00:00 +0000
System.out.println(formatter.format(dateTimeInDesiredZoned));

但是，2018-12-24 12:00:00 +0800和2018-12-23 16:00:00 +0000不是同一个瞬间。他们之间有12个小时的间隔，你需要减去这12个小时。

DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss Z");
OffsetDateTime offsetDateTime = OffsetDateTime.parse("2018-12-24 12:00:00 +0800", formatter);
offsetDateTime = offsetDateTime.minusHours(12);
ZonedDateTime dateTimeInDesiredZoned = offsetDateTime.atZoneSameInstant(ZoneId.of("UTC"));
// 2018-12-23 16:00:00 +0000
System.out.println(formatter.format(dateTimeInDesiredZoned));

Java如何把+0800改成+0000？

How to change +0800 to +0000 in Java?

java

datetime

simpledateformat

zoneddatetime