Java Programming Tutorial - 71 - JList Program Video Lecture - Java Programming

what is going on everyone hey guys doing
welcome to 70 first job tutorial and in
this tutorial we're gonna be adding some
functionality to this list we just made
on screen so let's go ahead and inside
her constructor so let's go ahead down a
couple lines and what we want to do is
add a selection listener to this list so
what we want to do is put list dot add
list well look at that already has it
for us add list selection listener and
then go ahead delete this because we're
not gonna need it and we're gonna make
just like last sort of you saw another
anonymous inner class so go ahead and in
your first line of the parameters for
add list selection listener what we
wanted to do is make a new anonymous
class and remember this is just an
easier way of handing it handling so put
new list and then see you listen
selection listener just like that it's
gonna take no parameters and we should
say must implement yep must implement
method value changed so this is pretty
much says whatever classroom aid
implements list selection listener it's
just a easier way of bypassing it the
thing is we need to make a method in
here called value changed that's what
it's telling us right now so in like
orders to fulfill our duties of
implementing it so let's go ahead and
make public void value changed in all
this is pretty much what you need every
time you make a J list so let's go ahead
and fir the parameters for this is list
selection event and go ahead and type
event and now we can go ahead and start
doing the stuff that we want to do so
pretty much aside from this all of this
stuff is pretty much built in Java and
you need this every time it's none of
your own custom stuff so it's just the
easier way of adding some event handlers
to your program so now that we got all
this housekeeping stuff done let's get
into the good stuff what do we want to
do when a user
clicks one of the colors well what we do
want to do in people language is select
that color and change the background to
that color so actually there's three
different layers on our window
the first there's a background there's a
content pane and there's something
called I think it's called a glass pane
now the content pane is on top of the
background so they have a set up a
really weird you need to actually access
the background through the content pane
in order to change background so the
first thing you need to do is get
content pane like that and the second
thing you need to do is finally we get
to our background so let's go ahead and
set background just like that and I
spout that around background that's a
little bit better and there we go my
hair goes away and so what do we want to
set the background to well in our
parameters for here let me just end this
statement and our parameters for here we
want to set it to one of these colors
from the color list color black color
blue color red color right so the first
thing we're gonna nuke you need to do is
add color and empty square brackets and
now what we want to appear in here is
one of the numbers one through four so
how can we get the numbers one through
four depending on what they selected
remember in our list was the array or
excuse me was the array color names and
our list was named list so let's go
ahead and put list dot get selected
index so it's automatically gonna know
whenever we do not want to put that
there
let's see so it's automatically gonna
know that in our list that we just
created and why am I getting a line
under color because it actually colors
there we go
so when whenever it clicks our list in
by it I mean we it's automatically gonna
know if we click the first second third
or fourth item
our list it's gonna get that number and
it's gonna say alright if you click the
third item in our list I'm gonna pass
three in four here so color is three
equals let's see colors zero actually
one two three so it's gonna be red so
that is how it happens like that and
remember to set the background you need
to get the content pane and get set
background I don't know why they did it
this way instead of just you know set
the background but they did it this way
and don't forget there's actually three
layers the content pane background and I
think it's called like a glass pane or
something something weird so that's that
for this story and let's actually run
this program and see if it works so I
see by default it's nothing because we
didn't send it to default value now when
you click black blue white red blue red
black white and any order then that's
pretty much just what happens so one
more time and let me walk you guys
through that the first thing we did is
import all our stuff make sure you have
those it's key trust me
and let's see let's get to the important
stuff we made a list which is a variable
further list we made the color names
which is what we saw on the screen and
we had a correspondent to the colors so
that Java can understand it using the
special colored black next we made a
constructor with a titled layout yada
yada yada we made a list and we set it
equal to J list color names which were
the options that the user can see set
the visible row count which was four
options by default then we made a single
selection so you can only select one at
a time and we made a J scroll pane which
gave us the scroll window if necessary
next we added all this stuff which is
pretty much the default stuff you have
to add in Java and finally we added this
little line right here we went to the
content pane so we could get to the
background and then depending on what
index they clicked we corresponding it
to list of colors that we made up here
so one is black twos blue threes red
four is white
so that is how we did that and that's
how we made an awesome little program
and look at this how awesome is that it
seriously red white and blue didn't even
notice it black where does that come in
but anyways thank you guys for watching
don't forget subscribe and I will see
you next tutorial