Java Programming Tutorial - 69 - Drop Down List Program Video Lecture -

what is going on everyone welcome to
your 69th java tutorial I've been making
a lot of Java tutorials I just noticed
and in this tutorial I'm gonna show you
guys how to add some functionality to
the box so what we need to do to add
functionality is add an item listener
and one item listener does is pretty
much this chills there and waits for you
to click something and when it clicks it
it pretty much just well tells it to do
something so let's go ahead and take
that box because that's what we want to
add an event to and we'll go ahead and
I'd add item listener there we go now as
you know an item listener usually takes
an event handler object as its parameter
well I'm gonna tell you guys how to do
something real quick here instead of
having a new object like handler and
having it passed into the handler class
what you can do is if you go ahead and
there we go just like that instead of
having an object and creating a whole
another outside class somewhere else you
can actually put something called an
anonymous inner class in here and what
this does is it actually implements the
item listener class so here's how you do
that go ahead and type a new item listen
or just like that and this is your
declaration for an anonymous class that
implements item listener so instead of
having like before handler class
implements item listener outside and we
have to make a whole new class what we
can do is just go ahead and stick a
class in here and pass it in for the
parameter as add item listener and we
bypass that entire step of having to
create a whole new separate class so
again since we named a none anonymous
class that implements item listener we
need to use that method and that's
called item state changed as you can see
right there so what this class has to
have in there is only one method that's
know let's go ahead and create it right
now
item listener has let's go ahead and
make it public
void item state change I gotta make sure
I spell that right and did I oh yeah
nice now what we have to do is of course
it takes in item event event just like
that and as our body for this we just go
ahead and write whatever we want to
happen when we selecting one of the
options and here's how you can do that
go ahead and make a if statement in this
if statement determines what option you
selected so if the events get state
change this pretty much if you click a
button we want to set it equal to or
excuse me we want to test if it's equal
to item event dot selected so what this
pretty much means all right did you
select a button is equal to what was
this pretty much means what was selected
just a nutshell so what will select it
first of all whatever you select do we
want to take that picture and remember
this is just the picture that appears on
your screen
we want to set icon which pretty much
means change the image to and the
parameter says what icon do you want
changed to well we have an array called
pix and what we have the thing is we
have two elements or two images in this
one
so what when do we select well go ahead
and type box dot get selected index with
empty parameters just like that make
sure typed everything right parenthesis
bam bam now make sure the method gets
state change is undefined type and oh
here we go hold on a second
all right guys in all of my excitedness
I did another stupid ear I actually put
get state change instead of changed
quite embarrassing make sure you type
that right but now pretty much that's
all we needed to do so what this does is
it makes anonymous inner class and this
is the class it's
and in this class the only thing we
needed to do is since the implement and
item listener we needed to add an item
state changed method since that was the
only method in item listener and then we
pretty much just said our right
while item did you select or what option
did you select in the drop-down list and
change the picture to that icon or item
so now we can go ahead and get out of
add item listener and we can pretty much
just add all this this screen so add
that box to the screen and remember that
box is just the drop-down box and now we
want to take that picture and add it to
the screen but by default let's go ahead
instead of equal to nu J label and we'll
do pix 0 and this pretty much just gives
a default value so you know something
appears before you choose any options
and lastly let's just go ahead and add
that picture to the screen just like
that and we shouldn't get any air should
it and now let's go ahead and just run
this and I'll show you guys what we get
by default again like I said we have B
on the screen which is at the end X is 0
then when we select X our picture
changes the X we can go ahead and select
B X we can do this all day if we want
really but no time for that we need to
overview our program so what we did is
pretty much let me get the good stuff we
made a box variable a picture variable
just a hold box and picture later on we
made an array of file names and we made
an array of images named pics and then
we went and go ahead and our constructor
which is pretty much making the window
we had a title editor layout we set that
box equal to new jcombobox
and it took the file names is the
options so again if I go ahead and run
this this these options right here are
the default for file name so that's why
that was able to run and the only
confusing part which we did new is this
instead of having a new object in a new
class we just went ahead and stuck the
handle
class inside the add item listener and
that was actually an anonymous inner
class and what we needed to do is we
needed to overwrite this method item
state changed because that was the only
method in item listener and we overrode
it with a nice little function right
here and then we went had to added the
box at a screen then we went ahead and
added the picture this screen and just
gave a default setting and we were good
to go so again here is our awesome
little program right here flawless no
bugs no anything so that's all you get
for this tutorial thank you guys for
watching in the next tutorial we're
gonna be going over something else cool
you can do with gooeys and well that's
it so again thank you guys for watching
don't forget to subscribe and I will see
you next door