JavaFX Java GUI Tutorial - 12 - ChoiceBox (Drop Down Menu) Video Lecture | JavaFX Java GUI: Learn to build Powerful Applications - Front-End Programming

alright guys in this video I want to
start talking to you about the different
kinds of lists that you can use in
JavaFX there are actually a couple
different kinds there are these things
called tree views which is actually kind
of like this see how you can like select
something and expands and it might give
you more options so this would be a tree
view they also have like combo boxes
where it kind of just looks like a bunch
of you know like a regular list and you
can like select multiple items in it at
once and you can also have like
drop-down lists and that's what this
tutorial is going to be about so again
you already know what drop-down list is
it pretty much is a drop-down then you
click it you get like a menu of stuff
and then you click one and that's your
option so the starting point for this is
just a button and I'll say whenever you
select an item and hit click me and this
is going to print out in the terminal
and all of these different types of
lists are of type observable list so if
I ever say observable list just think
JavaFX list so let's go ahead and figure
out a credit right now so under your
window a good place to put it actually
might as well put it under the button to
tighten this stuff up and actually let
me give myself a little bit more padding
all right so I drop down this is just
called a choice box why they named it
choice box instead of drop-down not sure
but they did and you can have a bunch of
different types of data in the choice
box you don't want to mix it up for
example you don't want to drop down
that's going to have strings and
integers in it together you can have a
drop-down for Strings and you can have
another one for integers but you don't
want to mix your dad together all in the
same arm observable list so I'm just
going to use this one for like names of
stuff so of course those are strings so
in between curly brackets type what type
of data do you want to store in your
drop-down now I'll just name it choice
box it set this equal to new choice box
object right like that and you actually
if we ever see this
some people actually type string on both
sides you don't need to do this since it
is implied alright so now we have a
blank drop-down list that's it pretty
boring let's go ahead and stick some
items in it so whenever you want to add
item to it there are a couple different
techniques and let me just say this get
items taste well observe or wrong and
add items to alright so what we're going
to do is we first need a reference to
the dropdown itself which is choice box
and then we call a method called get
items so this is going to get all of the
items in your list now I know it's empty
right now but whether you're adding the
tenth item or the very first item it
doesn't matter you still need to get all
the items currently in your list so
after this what you can do is you can
just say add and then you can add any
string to it for example apples let's
all make one for fruit so this drop-down
is going to let the user select their
favorite fruit so again you can go on
and keep doing this one by one you can
add another item banana be a na-na yes
that is how I remember spell bananas I
think it's gwen stefani thank you very
much
so you can either add items one by one
or what you can do is if you had a huge
list of items or an array then you can
call add all to add several at once so
I'm actually going to throw in arm
another fruit mine which is bacon I
think that's my favorite fruit and let's
just stick ham and um meatballs in there
so again these are some of my favorite
fruit so again what we did is we now
have five items in our drop-down and
these are just two different techniques
of adding those items
so let me actually show you guys how to
do this of course if you ever want to
add it to the screen which you probably
do then you just add it as expected but
check out what happens whenever you run
this by default we got our list
everything looks good but no option is
selected at first I mean we can select
bananas and meatballs
but again whenever the user launches
this program you probably want to have
some value in there so for a default
value oh sorry I got black alone from
work in the mines art so anytime you
want a default value just get a
reference to your drop-down and call set
value and again this is just going to
set an initial value but of course the
user can change this whenever they
actually select something so set the
default value now whenever you run it it
doesn't work because we need to set this
equal to a value that already exists
which is Apple this is instead of Apple
alright so there you go
so again whenever you have a default
value make sure that it's actually equal
to something that is already inside your
list the million box is open right now
alright so we know how to make a drop
down list and display on the screen of
course the next logical step we want to
do is implement some kind of method to
extract the value from it so I am just
going to add a button set on action
method and we'll just fill it on that
says like a get choice now of course we
need to pass in our choice box and make
the method
all right so would you say that's
private void get choice Teen Choice
Awards why did I say that no idea now
the object that we're passing in
remember I guess it's not going to
highlight for me but it's a choice box
string and I'm just going to call it
choice box so again what you can do is
whenever you're creating your drop-down
list you can just copy this and use it
in a parameter
whenever you're validating the data so
again this is what type of object we're
going to pass in this is what type of
data it's going to hold and now we can
just do whatever we want
we'll say food equals choice box get
value so again what this is going to do
is it's going to get the currently
selected value whatever option the user
selected and now we can just print it
out on the screen so system.out.print
food and did I mess anything up
hopefully nuts all right so now if we
click it will just print out the default
value of course we can select something
else
bacon meatballs probably want to add a
new line there but whatever and there
you go so yeah simple is that you can of
course like I said print line and then
I'll kick it off onto a new line instead
of printing it all on the same line but
there you go that is how you use
drop-down lists how you add items to
them how you set default values and of
course how you extract the user's choice
or selected item so thank you guys for
watching see you guys next time