问题描述
在各种Android项目中,我使用以下静态函数来解析日期,例如 1900-12-31
。当然,此功能应该是确定性的-但事实并非如此。为什么?
In various Android projects, I use the following static function to parse dates such as 1900-12-31
. Of course, this function should be deterministic - but it turns out it is not. Why?
通常,它会将日期 2010-10-30
解析为正确的<$拥有该值的c $ c> Date 实例。但是我注意到,当我同时运行 IntentService
并解析某些日期时,此函数将与上述相同的日期解析为 1983- 01-20
,这是 IntentService
中解析的日期之一。
Normally, it parses the date 2010-10-30
, for example, to the correct Date
instance holding that value. But I have noticed that when I have an IntentService
running at the same time and parsing some dates, this function parses the same date as above to 1983-01-20
, which is one of the dates parsed in the IntentService
. How can this happen?
public static Date dateFromString(String dateStr) {
SimpleDateFormat mDateFormat = new SimpleDateFormat("yyyy-MM-dd", Locale.getDefault());
SimpleDateFormat mDateTimeFormat = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSSZ", Locale.getDefault());
Date dateOut = null;
try {
if (dateStr != null) {
if (dateStr.length() == 7) {
if (dateStr.startsWith("--")) {
dateStr = "0000"+dateStr.substring(1);
}
}
else if (dateStr.length() == 6) {
if (dateStr.startsWith("-")) {
dateStr = "0000"+dateStr;
}
}
else if (dateStr.length() == 5) {
dateStr = "0000-"+dateStr;
}
else if (dateStr.matches("[0-9]{2}\\.[0-9]{2}\\.[0-9]{4}")) {
dateStr = dateStr.substring(6, 10)+"-"+dateStr.substring(3, 5)+"-"+dateStr.substring(0, 2);
}
else if (dateStr.matches("[0-9]{2}\\/[0-9]{2}\\/[0-9]{4}")) {
dateStr = dateStr.substring(6, 10)+"-"+dateStr.substring(3, 5)+"-"+dateStr.substring(0, 2);
}
else if (dateStr.matches("[0-9]{8}")) {
dateStr = dateStr.substring(0, 4)+"-"+dateStr.substring(4, 6)+"-"+dateStr.substring(6, 8);
}
if (dateStr.length() >= 20) {
String dateTimeStr = dateStr.trim();
if (dateTimeStr.endsWith("Z")) {
dateTimeStr = dateStr.substring(0, dateTimeStr.length()-1)+"+0000";
}
if (dateStr.charAt(10) == ' ') {
dateTimeStr = dateStr.substring(0, 10)+"T"+dateStr.substring(11);
}
try {
dateOut = mDateTimeFormat.parse(dateTimeStr);
}
catch (Exception e2) {
dateOut = mDateFormat.parse(dateStr);
}
}
else {
dateOut = mDateFormat.parse(dateStr);
}
}
}
catch (Exception e) {
dateOut = null;
}
return dateOut;
}
编辑:我在活动
的 onCreate()
,在此我启动一个 AsyncTask
做这份工作。在活动
的 onStop()
中,启动了后台服务,其功能相同。当我关闭应用程序(onStop())并快速重新启动它(onCreate())时,似乎两者都同时运行,并且发生了错误。
I do the parsing in my Activity
's onCreate()
where I start an AsyncTask
that does the job. In the Activity
's onStop()
, a background service is started which does the same job. When I close the app (onStop()) and quickly restart it (onCreate()), both seem to be running simultaneously and the error occurrs.
推荐答案
说:
您去了。只需在每个线程中分别创建 SimpleDateFormat
对象,然后将其传递给该方法即可。
There you go. Just create the SimpleDateFormat
object separately in each thread and pass it to the method.
这篇关于在Android中解析日期时出现意外的副作用的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持!