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We have valid data in our app, but not all of it is useful in its current form. Let's see how to convert a UNIX timestamp into a more meaningful time string.
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The data model for
our app is coming along quite nicely.
0:00
We've accomplished a lot those far,
with parsing
0:04
the days on formatted weather data, and
getting it into our current weather model.
0:06
However, if you recall from our
time value, it was a bit unwieldly.
0:11
Let's take another look at
the documentation for our API,
0:17
and see what we can discover.
0:21
If we go back to the dark
sky documentation, and
0:23
click on the response format link,
we see a list of the various object,
0:26
and their properties that
are returned from the API call.
0:33
We're working in the currently object.
0:37
So let's click on this data point
link here for additional information.
0:39
If we scroll down a bit,
we see the time property.
0:43
It says that this is the Unix time
where this data point begins.
0:53
What is UNIX time though?
0:58
UNIX time is a system for describing time,
you find is the number of seconds
1:00
that have elapsed since
coordinated universal time, UTC.
1:04
UTC started on Thursday,
January 1st, 1970.
1:09
You may also hear this referred to,
as the UNIX Epoch.
1:14
I know.
1:18
Leave it to developers to
represent time in a crazy fashion.
1:18
But, this is a very standard way
of handling time on UNIX systems.
1:22
And fortunately, there are several
built-in methods to handle this format.
1:27
Our mock-up calls for the time to be
displayed in an easily readable format.
1:34
Right now however,
our time is in a huge number of seconds.
1:38
We'll need to convert that into
a more human readable format, and
1:42
put that time string into a text view.
1:46
Notice too that we're just wanting
the time portion of the time since
1:48
the UNIX Epoch,
we're not concerned about the date.
1:52
Let's add a new method to the current
weather class called, getFormattedTime.
1:55
We can use the simple date
format class to help us out.
1:59
Looking through the documentation for
a simple date format, we see that it can
2:05
take in date and time values in
different formats, including UNIX time.
2:09
It can then convert them
into local specific time.
2:14
This is exactly what we're looking to do.
2:18
The way this works, is that we create and
configure a formatter object.
2:20
Then use it to format a date value.
2:24
There's a list here of all the different
format symbols we can use.
2:27
Recall from our mock-up, if we want
the time to be in the format of hours
2:30
without a leading zero
if it's a single digit.
2:35
Then minutes, and then AM or PM.
2:37
Let's head back to current weather,
and create our formatter, and
2:41
set our time value.
2:44
So back here in CurrentWeather,
2:54
let's add a getFormattedTime method,
under getTime
2:56
public, will return a String, called
getFormattedTime.
3:06
Inside here, we'll put SimpleDateFormat
to use and build our formatter.
3:17
SimpleDateFormat, call it formatter.
3:23
Be a new SimpleDateFormat,
hours without a leading zero, minutes,
3:30
including that leading zero, and then a,
which will give us our AM or PM.
3:38
We're getting the time value from the
forecast, from the location we specified.
3:44
In our case, that's Alcatraz Island,
3:49
which resides in the San Francisco Bay
of California, in the United States.
3:51
And, it's in the Pacific Time Zone.
3:55
Therefore, we need to set the time
appropriately with the time zone in mind.
3:58
So we can do formatter.setTimeZone.
4:04
For our parameter in here, we can use
a helper from the Java TimeZone class.
4:11
TimeZone, getTimeZone, in here,
we need a time zone code as a string.
4:18
Seems like we've seen
that somewhere before.
4:26
Let's look at getCurrentDetails
over in main activity.
4:29
There it is.
4:34
We're logging it here
in getCurrentDetails.
4:35
Let's add it to our data model,
so we can use it.
4:38
Make it a private, String, timeZone.
4:45
Now back in MainActivity,
4:51
we can set our timezone using
the timezone variable we already have.
4:53
CurrentWeather, setTimeZone,
5:02
Passing time zone.
5:11
And it looks like we need to go back, and
generate our getter and setter for that.
5:13
So Code, Generate, Getter and
5:19
Setter for timezone, great.
5:24
No more error there,
if we go back to CurrentWeather.
5:32
And we can use that timezone, in here.
5:38
Our formatter is ready.
5:47
We just need to return it.
5:49
Return, formatter.format().
5:54
Now here's the tricky part.
6:01
Working with dates can be a challenge,
it can require a lot of trial and
6:03
error in readings or documentation.
6:08
We need to pass in
a Java Date object here, so
6:10
let's look at the Date documentation.
6:12
We look here in the Constructor Summary,
6:18
there's a constructor here that
takes a time value as a long.
6:20
Nice.
6:25
That's what we're already have.
6:26
Well, wait a second.
6:28
It says here that it needs
to be in milliseconds.
6:30
Our time value is currently in seconds.
6:33
So we need to make that conversion first.
6:35
This can be super frustrating, and
cause lots of headaches, if you don't
6:37
realize that the time needs to be in
milliseconds, and you pass in seconds.
6:42
Fortunately, it's an easy fix.
6:46
We simply need to multiply
our seconds by 1,000,
6:49
since there are 1,000
milliseconds in a second.
6:52
So we'll do Date dateTime, do our import.
7:00
We want the java.util.
7:05
Date (time * 1000),
7:09
I forgot an equal sign,
7:13
that would be good to have.
7:17
Now we can pass this into
our time string formatter.
7:24
All right, let's test this out
by calling this new method, and
7:30
logging it in MainActivity in
the getCurrentDetails method.
7:34
So MainActivity,
getCurrentDetails, down here.
7:40
Log.d, our TAG,
currentWeather.getFormattedTime().
7:44
And let's remove this breakpoint, since we
won't be using a debugger at the moment.
7:55
And we'll run our app.
7:59
And look in the Logcat.
8:10
And there it is, our formatted time,
very cool, this will be ready for us,
8:14
when we get to working
on the user interface.
8:19
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