You need to override onSaveInstanceState(Bundle savedInstanceState)
and write the application state values you want to change to the Bundle
parameter like this:
@Override
public void onSaveInstanceState(Bundle savedInstanceState) {
super.onSaveInstanceState(savedInstanceState);
// Save UI state changes to the savedInstanceState.
// This bundle will be passed to onCreate if the process is
// killed and restarted.
savedInstanceState.putBoolean("MyBoolean", true);
savedInstanceState.putDouble("myDouble", 1.9);
savedInstanceState.putInt("MyInt", 1);
savedInstanceState.putString("MyString", "Welcome back to Android");
// etc.
}
The Bundle is essentially a way of storing a NVP ("Name-Value Pair") map, and it will get passed in to onCreate()
and also onRestoreInstanceState()
where you would then extract the values from activity like this:
@Override
public void onRestoreInstanceState(Bundle savedInstanceState) {
super.onRestoreInstanceState(savedInstanceState);
// Restore UI state from the savedInstanceState.
// This bundle has also been passed to onCreate.
boolean myBoolean = savedInstanceState.getBoolean("MyBoolean");
double myDouble = savedInstanceState.getDouble("myDouble");
int myInt = savedInstanceState.getInt("MyInt");
String myString = savedInstanceState.getString("MyString");
}
Or from a fragment.
@Override
public void onViewStateRestored(@Nullable Bundle savedInstanceState) {
super.onViewStateRestored(savedInstanceState);
// Restore UI state from the savedInstanceState.
// This bundle has also been passed to onCreate.
boolean myBoolean = savedInstanceState.getBoolean("MyBoolean");
double myDouble = savedInstanceState.getDouble("myDouble");
int myInt = savedInstanceState.getInt("MyInt");
String myString = savedInstanceState.getString("MyString");
}
You would usually use this technique to store instance values for your application (selections, unsaved text, etc.).
java.util.Date
has no specific time zone, although its value is most commonly thought of in relation to UTC. What makes you think it's in local time?
To be precise: the value within a java.util.Date
is the number of milliseconds since the Unix epoch, which occurred at midnight January 1st 1970, UTC. The same epoch could also be described in other time zones, but the traditional description is in terms of UTC. As it's a number of milliseconds since a fixed epoch, the value within java.util.Date
is the same around the world at any particular instant, regardless of local time zone.
I suspect the problem is that you're displaying it via an instance of Calendar which uses the local timezone, or possibly using Date.toString()
which also uses the local timezone, or a SimpleDateFormat
instance, which, by default, also uses local timezone.
If this isn't the problem, please post some sample code.
I would, however, recommend that you use Joda-Time anyway, which offers a much clearer API.
Best Answer
RFC 3339 describes a specific ISO 8601 'profile' for date/time representation.
If using 3rd-party open-source libraries is an option, take a look at Joda-Time's
ISODateTimeFormat
utility class.Otherwise, if you need to roll out your own code it's not enough to use a
SimpleDateFormat
because of the way ISO 8601/RFC 3339 represents timezone information.If all you need to parse is in 'Z' (Zulu or UTC), then it's relatively simple:
Should print out "2011-08-11T01:23:45.678Z" in your local time zone.
If you need to handle arbitrary timezones in RFC 3339 then you'll need to extend the above to parse out the timezone designator and retrieve the corresponding Java
TimeZone
instance. That shouldn't be too hard if it's just whole hours +/- GMT, but in case of non-standard offsets you may have to create your ownSimpleTimeZone
instance.