Android Application Development Tutorial - 100 - File Input Stream Video

what's up guys welcome to your big 100th
Android tutorial forward the new Boston
if you've made it this far give yourself
a pat on the back yeah I don't know
about that intro I was trying to do
something crazy since I'm going crazy
after a hundred makin hundred tutorials
talking to the computer screen you tend
to go crazy a little bit I don't know
why Bucky isn't in an insane asylum
right now because he's done so many but
so what we're gonna do in this tutorial
is learn how to load data with this
button load and in the next tutorial
after this one I'm gonna show you guys
how to properly save and properly load
data because yeah this is the frame this
is I mean nothing new for the most part
this is how you do it you with file
input and output stream but there's a
better way that you want to code so I'll
show you that in the next tutorial but
first let's get into it let's start our
load button here so what we're going to
do is we're gonna create a file input
stream now so we're gonna just say file
input stream and we're gonna call this
fi s for file input stream because again
file output stream is to save data and
this is to kind of read the data load
the data all that good stuff so what
we're going to do is we're going to set
this equal to open file input instead of
open file output like we did with in our
on create method and again just within
the within these parentheses we're just
gonna say our file name again that's our
string reference kind of our path name
and again we're gonna have to surround
this with a try and catch so we're just
gonna say surround with try and catch
right here and within here after we open
it
we want to set up a byte array so what
we're gonna do is we're gonna say byte
[Music]
array which is basically going to read
all the data all the bytes and all that
stuff so we're just gonna say data array
something like that and we're going to
set this equal to is a new byte and
we're gonna reference within our square
brackets here's just getting the length
of our file input stream so we're gonna
say file input stream dot available and
basically that's going to return the
amount of you know bytes this file input
stream has so it's just setting our
array up to the same length as whatever
however many bytes is in our file input
stream so again we get in there we just
need to add another catch Clause to our
surrounding try and that's an input
output stream exception and now what
we're gonna do is we're going to say
while file input stream dot read does
not and we're gonna say read data array
like this and I'll explain everything as
we go here and does not equal negative
one so what we're doing here let me just
talk over everything real quick we set
up a file input stream which is
referring to our file name which is that
string reference then we're getting
setting up a byte array and that's
basically gonna get the length of our
input stream how many bytes it is and
then we're gonna do is say while it is
not equal to negative one so what's
going to do is it's gonna read through a
file input stream and once it reads
through everything it's gonna set this
read up to negative one so once it hits
negative one we know we've read
everything for the most part so that's
just what this means it's pretty
standard in Java and all that stuff but
just know that this negative one just
means we've read everything for the most
part from our file input stream
which has the length or this many bytes
for the most part because that's what we
set up here so now what we're gonna do
is we're gonna create a string so we're
gonna call this collected something like
this and above our try we're just going
to set up this string here so string
collected initially equals null when we
hit our load button and then we're gonna
set this collected string equal to a new
string and within here we're gonna say
our data array and then all we have to
do is close or file input stream so what
we can do is we can either say like
close right here or what we can do is
kind of refer to just to get again
familiar with the try-catch and finally
we can also say finally referring to
after everything's done we kind of did
this with our splash activity I believe
so we're just gonna say finally file
input stream dot close and it's gonna
give us an error because we set up our
file input stream within this try so
what we're also going to do is just copy
this or cut it and then just say file
input stream and again above our try
we're just gonna hit paste equals null
and then we have to surround this with a
try and catch as well so we're just
gonna hover over and say try and catch
and it looks kind of complicated but
it's really not that bad and that's
pretty much this tutorial let me talk
through everything that we've done so
basically we set up a string called
collected this is going to be all of our
data that we breed we set up a file
input stream and both of those are null
and then once we try once we try to get
our file input stream set up what we're
going to set that up to equal is opening
file input referring to the file or
referring to the string name which is
basically you can think of as a path of
some sort and then what's going to do is
it's gonna read that that file input
stream and get how many bytes is
available and that's gonna set up a byte
array which we call data array
then while our file put in our file
input stream is reading all of those
bytes for the most part and as long as
that's not equal to negative one because
when it equals negative one we're done
it's going to break out of our while
loop and while that's happening we set
up the string which was null and now
it's just gonna equal a new string
according to the data that it's reading
for the most part again our bit array as
it cycles through this while loop
they'll add to that as well so it's
gonna basically be whatever is our data
that we saved and then we have these
catch exceptions for file not found and
file our input output exception and then
we say finally after everything's done
just close our input stream and we need
to surround that with a trying to catch
as well so input output exception here
as well so hopefully you guys kind of
understand that it's it's not too
difficult for the most part and also we
can do is we can now set our textview
equal to the data that we read so what
we're gonna do is say our text view
which we call data results and then dot
set text and then we're gonna set it up
to this collected string that we read
for the most part so now it's going to
change that textview when we hit the
load button yeah this does look a lot
more complicated for the most part than
the shared preferences and if you again
you're just saving one variable like a
string you probably want to use shared
preferences but I just want you to get
you guys familiar with the input/output
streams and working that way because
when we work with external data that's
kind of the concepts that we're gonna
have to know so thanks again for
watching guys hopefully it wasn't too
confusing and I'll catch you guys in the
next tutorial peace