Android Application Development Tutorial - 101 - Asynctask class to load

what up everybody welcome there hundred
and first Android tutorial for the new
boss in what we're going to do in this
tutorial is learn about the async task
class and basically what that's going to
allow us to do
I will actually first let's talk about
our problem that we're having for the
most part or app activity works we can
load data we can say I'm sorry we can
save data and we can load data but the
problem we're having is sometimes you
know loading data might take some time
if it's a big file or something like
that that's read to through a ton of
bytes of data and right now what we're
doing is this we're doing all that stuff
within the same thread as our user
interface like the thread that handles
our button clicks or touch methods
everything else so you know it's pretty
pretty busy and then we add something
like saving and loading data to that
it's like hey man I'm doing everything
you know start your own thread if you
want to do some extra crap so that's
what basically the async task is going
to allow us to do we're going to be able
to load data on a separate thread so it
won't really affect our processing speed
not process it won't really affect our
you know won't really stress out our
user interface thread because if that's
too stressed
it'll slower application if it's it's if
it goes on pause for more than five
seconds that's going to crash your
activity so we're just going to create a
new thread that is going to handle our
loading data in this tutorial and what
we're going to do at first is we're
going to cut everything from what we did
in the last tutorial within our load
button so it should look pretty bare and
make sure you cut it copied it because
it's going to be pretty much the same
code and now what we're going to do is
we're going to create a new class that
extends the the async task class so we
can you know loader data there but how
we call that method or how we call that
class to kind of you know do whatever we
want it to do is we're just going to say
new load some
we're gonna say new and then our class
name we haven't created yet so we're
just going to say new load some stuff
which is going to your class name with
two parentheses and then we say dot
execute whoa can't spell and then we're
going to give it a file name something
like that now what we need to do is
create this class called load some stuff
and have it extend the async task so
we're going to go right above our last
bracket within our you know our class
here our internal data we're going to
set up a new class so we're going to say
let me say public class load some stuff
and then we're going to say extends
async task and then we're going to give
one of these greater than signs I'm
going to say string integer and string
and I'll describe what that means here
in a second so now we have this load
some stuffed class and it's given us an
error because we have to implement a
method because we're using the async
task so we're going to say add
unimplemented methods and it creates
this method doing background now what
we're going to do is just kind of paste
everything from the previous tutorial
within this doing background so again we
just created this you know new execute
method for the most part and we pass in
a string and once this execute method
gets cold it's going to go to our class
name which we called load some stuff and
it's going to do this method do in
background so in the background it's
going to kind of load all our data that
we want so we're just going to hit
control V for paste and what we're going
to do is with this method is looking to
return something so instead of saying
you know setting our text here which we
could still do we're just going to say
return collected
and again collected was that string
right here that we get or that we set up
that reads kind of our data from our
file input stream again that we created
in the last tutorial so after all that
happens if everything works properly
it's going to close our file input
stream and it's going to return the
string called collected so now let's
talk about this setup here as we as you
can see we extended the async task class
and now let's talk about these three
parameters the first parameter is saying
hey what is being passed in and since
we're passing a file name which is a
string we're going to set up this first
reference as a string as well or
whatever you're passing in the second
reference is for kind of a progress or
update bar so we're going to work with
integers I'm not sure if I'm actually
going to show you guys that or not we
might but I'm not positive yet and then
the third one is what we're returning
and again we're returning another string
called collected so that's what those
parameters are again what we're passing
in what our progress is and what are
what we're returning for the most part
and then again this doing the background
method is what is cold when we execute
so it's just going to create a file
input stream load everything and pretty
much everything we did in the last
tutorial now that's probably the end of
this tutorial since we got you know our
async task set up and we learned about
this do in background method I'm going
to show you guys some more methods that
we can use with this async task class as
well so I'll catch you guys in have a
good one peace