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The weather data is being returned in a format called JSON, which stands for JavaScript Object Notation. Let’s take a look at the data itself to help explain what JSON is and how it is used.
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As I've mentioned, the weather data we
are receiving is in a format called JSON.
0:00
It's one of my favorite data formats.
0:05
It is very versatile, and it can be
found and used in many applications.
0:08
Let's take a look at the weather data
to help explain what json is and
0:12
how it's used.
0:16
Let's head back to the Dark Sky URL
we looked at previously, and
0:18
examine our data.
0:22
JSON is spelled J-S-O-N and
is in all caps.
0:24
It stands for JavaScript Object Notation.
0:28
The idea behind JSON is that, data can be
represented in a simple to read manner.
0:32
It is easily parsed and used by
programming languages, data from websites,
0:37
can be returned in a variety
of different formats.
0:41
JSON is a popular choice to use for
mobile applications,
0:45
because it's easy and efficient.
0:48
An important consideration
when dealing with mobile apps,
0:50
is the size of the data
package being transferred.
0:53
JSON is minimal compared
to a format such as XML.
0:57
This is a big benefit for
users on slow network connections or
1:00
users get charged for data.
1:04
Additionally, and a big reason I like
JSON so much, is that JSON data is
1:06
represented as objects in a similar
way that many programming languages,
1:11
like Java, handle data.
1:16
However, JSON is just all data.
1:17
There are no methods in the objects,
just properties.
1:21
JSON is built on and can be represented
by two types of structures.
1:25
The first is a collection of key-value
pairs that can be grouped together
1:30
into an object.
1:35
The second is an ordered-list of objects,
we can think of this as an array or list.
1:36
These two data structures
are universal and
1:42
have support in virtually all
modern programming languages.
1:45
As such it makes a lot of sense to
use JSON as a data format with its
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interchangeability with
different languages.
1:53
If the JSON data is an object or
dictionary,
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it begins with a left curly brace and
ends with the right curly brace.
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Each key in the key value pair
is followed by a colon, and
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key value pairs are separated by commas.
2:09
On the other hand, if the object is
an ordered collection of values, or
2:12
an array, it begins with a left bracket,
and ends with a right bracket,
2:16
with each value being separated by commas.
2:21
Let's see how our data from our
weather query is structured.
2:24
Taking another look at our weather data,
with this in mind,
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we see that we have one object at the root
level, designated by this curly brace.
2:31
We can contract it, and expand it there.
2:36
So we see that our first items in
our object are a few properties,
2:40
with a key on the left and
a value on the right.
2:44
With our JSON extension installed,
this version is pretty readable.
2:48
If we switch over here to the raw format,
we see that the key for
2:53
every property is surrounded
in double quotes.
2:57
The colon separates the key from
the value, and if the value is a string,
3:00
it is enclosed in double quotes.
3:04
If the value is numerical,
it's just in plain text.
3:06
Switching back over to the easier to read,
pretty printed version.
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Lets take a look at
the key named currently.
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What sort of data is its value?
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This is where JSON is great.
3:23
See the curly braces here?
3:25
As I mentioned,
curly braces denote a JSON object.
3:27
So the value of the currently
key is another JSON object.
3:31
This is a great example of how JSON
objects can be nested within each other.
3:36
There's another aspect of the overall
JSON object I'd like to touch on.
3:40
Although we won't be using
it in our stormy app.
3:45
Take a look at the minutely object and
the data property.
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Those square brackets
denote it's an array.
3:52
This data element is an array of data
points providing minute by minute weather
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detail.
4:00
Each in item in the array is a JSON object
and each object is separated by commas.
4:00
One thing to note here,
in this particular example,
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each object, inside the array is the same.
4:09
This makes sense for this data,
4:12
since each minute the weather data would
be reporting the same information.
4:13
JSON arrays however,
can hold different types of objects.
4:17
That's a brief introduction to
JSON data and how it's structured.
4:21
You'll come across JSON data much
more in your development career, so
4:24
having the foundational
knowledge of it is important.
4:28
Fortunately, the Android SDK offers
some very helpful classes for
4:31
working with JSON.
4:35
We'll use them in a moment to populate
our current weather model object.
4:37
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