Is SimpleDateFormat in Java and Android different?

问题

When we call parseJavaAndroid("2018-04-27T22:31:07.962-05:00") from JVM it gives ParseException while a call from Emulator/Android Real device it works fine.
When we change SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSSZZZZZ", Locale.ENGLISH) to SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSSXXX", Locale.ENGLISH) in Android, it throws:

IllegalArgumentException with message "Unknown pattern character 'X' method".

It works fine in JVM and gives ParseException in Emulator/Android Real device.

public static Date parseJavaAndroid(String fromDate){
    SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSSZZZZZ", Locale.ENGLISH);
    Date date=null;
    try {
        date = format.parse(fromDate);
    } catch (ParseException e) {
        e.printStackTrace();
    }
    return date;
}

What should have to do then it works in both JVM and android real time device(minSdkVersion:19). I want pattern for "2018-04-27T22:31:07.962-05:00" which works on both Android as well as Java.

Note: The individual pattern is working, so Please don't suggest for individuals.

回答1:

I can't tell about Android, but in the JVM, the Z pattern recognizes only offsets without :, such as -0500, while the X pattern can recognize -05:00: https://docs.oracle.com/javase/7/docs/api/java/text/SimpleDateFormat.html

Perhaps Android has a different implementation, where Z also recognizes offsets with :, such as -05:00.

I'm afraid there's no one-pattern-fits-all solution: Z doesn't work in JVM, X doesn't work in Android, how to make it work in both? I think the best you can do is to try both patterns, something like this (in pseudocode):

try {
    parse with X
} catch(Exception e) {
    X didn't work, parse with Z
}

A much better alternative is to use the threeten backport and configure with ThreetenABP - or use java.time classes if your API level is 26:

// parse input
OffsetDateTime odt = OffsetDateTime.parse("2018-04-27T22:31:07.962-05:00");

// convert to java.util.Date (threeten backport)
Date date = DateTimeUtils.toDate(odt.toInstant());

// or, if you have java.time (API level 26)
Date date = date.from(odt.toInstant());