Android Application Development Tutorial - 21 - Finishing ListActivity Video Lecture | Android Application Development (Mobile App) - Software Development

what's up guys it's me Travis welcome
your twenty first Android tutorial for
the new Boston what we're going to do in
this tutorial is basically finish our
you know finish our splat our sorry our
list activity and kind of talk through
all this nonsense that's going on
because I know most of you guys are
confused so first thing we need to do is
get rid of this error for the most part
and we're just going to go over and see
what there is it says surround with a
trying catch because basically we could
say whatever we want we could say you
know starting-point blah blah blah and
be like yeah create a class for that and
be like hey you tried to trick me
there's no class like that and I spent
the past four hours trying to do that
and you know basically our application
isn't going to look like that so we need
to surround this with a try
so we're going to go above here and type
try and put a bracket and then we're
going to also close off our try bracket
right here after we try to start the
activity and then we get rid of that
error the next thing we need to do is
catch an exception for example we're
going to use the exception type class
not found so again if this class is not
found it's going to give us that
exception so we're going to say catch
and then we have to define the exception
within parentheses again the exception
type is called class not found exception
we're going to label this exception or
this are give this variable the type or
I'm sorry the label II and then we need
to create a new bracket and I'll try and
keep all the brackets so you guys can
keep track of everything I remember that
it's kind of difficult when I was a new
programmer so there we go
Yatta print stack trace again this is
just for debugging we'll get into this
stuff later probably maybe I mean it's
not too important it's basically going
to throw it around and not worry about
it so there we go we kind of have our
brackets set up but now let's actually
get into making this application useful
because now each time an item is clicked
it's just going to start up our starting
point class so what we want to do is we
want to have it start up a class
according to the items that's clicked
but before we before we actually do that
let me just do an overview of what this
application
it's doing and what we set up so we set
up a string rave up here called classes
and we set up a list array or a list
adapter which is basically like a list
view and within the list view it has
list items which we defined here I'm
just the standard kind of look of the
list item here and each list item is
going to have one position within our
string array so we're going to have
seven list items total and when each or
when any of those list items are clicked
it's going to call this on list item
clicked method and it's also going to
give us some information it's going to
give us what basically which list view
was clicked it's going to label that l
it's going to tell us which view is
clicked it's going to label that V and
the most important one that we're
actually going to use it's going to tell
us the position of within the list view
that was clicked and basically that's
going to coincide with the position of
our string array so we know kind of the
text that was clicked as well for the
most part think of it like that
it also tells us an ID so what we're
going to do is go right within these
brackets here and we're going to set up
a new string we're just going to call
this string local class alright I don't
know we're going to call it cheese just
so we don't have to think and you know
all that good stuff so what we're going
to set this string equal to is basically
we're going to say like our classes
array that we set up at the beginning
and we can set it up to something like
you know four for example and basically
what this would be equal to or this is
the fourth position within our class way
up here so we have position 0 1 2 3 & 4
so basically it's the same thing as
saying at the moment it's the same thing
as saying this so we don't want to
actually do that but that's kind of how
this variable is going to work our
cheese variable is going to be equal to
just one spot of our classes array but
since we're getting the position it's
giving us that data we can use this
variable that they called position
within this class oh I'm sorry and we
won't also move this string below the
super line right here so I'm sorry for
that but okay there's our string
variable and we can you
this position kind of data that's being
passed in so we can just say position
within here because again it's a integer
so it's going to tell us what position
was clicked
so now cheese equals basically the
position so the zero position was
clicked this cheese variable is going to
equal starting point the fifth position
was clicked it's going to equal example
five so now what we can do is we can set
up a class according to which position
was clicked or which list item must
click so we can do that by using the
string variable because again this class
method basically is using a string with
its parentheses so what we can do is we
can delete this but still make sure you
have your period there after your
package name and we can just say plus
string or I'm sorry plus cheese that's
thinking a string cheese because that's
delicious but there we go so now it's
going to open base or give this path to
whatever list item is click so if
position 0 is clicked is going to say
our package name plus you know starting
point and then it's going to create a
class variable and then it's going to
set up an intent according to that class
variable again I show you guys a new way
to do it where it takes a context and
then at a class variable and then it's
going to start that activity now if if
we click for example position five again
it's going to set this equal to examples
five and it's going to try to set up a
class variable for in our package name
example five but since we don't have
that we're going to get an error and
it's not going to work or it's not going
to work I'm sorry I said that twice it's
basically just not going to work since
we don't have that class and it's going
to catch or it's going to create an
exception called exception not found and
we're just going to kind of log that
within the debugger so that's what that
catch is doing so hopefully that kind of
made sense guys but that's kind of how
you can use java by instead of typing a
ton of lines of code you can just kind
of use these paths or getting some
information from a method and then use
it within there to you know do that the
only other thing we're going to do real
quick is set this up in the manifest so
we're going to go into the manifest and
I'll spin mess around with this so just
going to fix it real quick your manifest
should be looking like this and so what
we're going to do is we're just going to
copy the starting point activity and
paste it again below and we're going to
change this to our new class called menu
we're going to give this the action name
menu then what we're going to do is
we're going to open our splash class up
here and change instead of AFRICOM
instead of it's starting up the
starting-point class we want to start up
this menu class so we're just going to
use the action name that we just set up
in the manifest so there you go
now our application should be working
I'm just going to test it out make sure
I don't get any errors again I know
that's guys I know this is probably
confusing you probably don't understand
everything or maybe even 5% of that list
activity you guys understand don't worry
because it's going to get easier we're
going to get into some simple stuff in
the next tutorial so thanks again for
watching but there we go we have our
list activity started and if we click
like examples 1 2 3 it's not going to do
anything it's going to throw that
exception but if we click starting point
it's going to open up our starting point
class so and again we did that through
setting up a class variable instead of
using the action name so thanks again
for watching guys I'll catch you in the
next tutorial have a good one