Java Programming Tutorial - 38 - Public; Private and this Video Lecture

sup guys welcome to your 38th java
tutorial and in this tutorial I'm going
to show you guys how to control access
to different variables in other classes
and also what the this keyword means in
Java so let's first of all talk about
access to these private variables right
here now what private means is that
these variables are private meaning that
only these methods have access to it
only these methods in the same class
this tuna class can use these variables
so what if we try to use these private
variables in another class like our
apples one well let's go ahead and try
to do that right now first of all we
already made a tuna object to use all
the stuff in that class but let's go
ahead and try to use something like our
right here if we go ahead and try to use
our and change it to like another number
we get this little um error right here
in a freer to run this would get a
compilation error so I don't want to do
that so what it says is the filled tuna
hour is not visible and that is because
instead of public it is private again
meaning that only these methods right
here can use it so if we want to change
that and put it so these variables can
be used in any class outside we need to
change that to public and now you can
see my little X went away so now I can
use the class outside to change the
variables in another class so let's go
ahead and change it back to private and
make sure you spell it right that's kind
of important and go ahead and delete
this and that brings me to another point
what the this keyword is in Java so what
if you're saying that all right I got
three variables in this class name hour
minute and second but also in my
constructor in or if this doesn't even
matter it can be your constructor or
just another function or excuse me
method I'm in talking about C++ for too
long
changes the hour minute and second
so now probably need to change these two
don't you think minute and second so
what if we were to say that these
variables in this method inside this
class we're the exact same as these
variables right here so in other words
if the constructor or any other method
uses names or variables identical to
instance variables then what when you
run the program what's it going to do
well let's go ahead and see right now um
I guess we don't need this anymore but
we'll keep it anyways let's go ahead and
run this and as you can see we get one
two three one two three and then we set
the time which doesn't matter anymore
then we get one two three one two three
so my point is that is this anytime you
have the same variables and a method or
constructor or the same thing um you
Java looks to these variables the local
variables instead of these right here so
retain all right that's good at all and
by the way you should never name these
variables the same as this this is just
a foreknowledge but um anyways so what
if we want to use that these variables
of four or five and six instead well if
the method contains a local variable
with the same name as the field names
right here then the method is always
going to look at the local variables
instead it's always going to look at
these instead and that is there is only
one way to kind of overpower this and
that is the use of this reference to
refer to these variables instead so for
example you know we had one two three
one two three one two three one two
three well if we use a little keyword
called this instead then it's going to
refer to these variables so this our
this
and this second and this pretty much
means this method right here that we're
talking about so anytime you use this it
says all right
don't use all these use this right here
and I'm sure that's a tone when he was
creating this use this one right here
I'm sure he said that so now if we go in
our main apples program and go ahead and
run it we now get one two three one two
three before oh four five six four five
six so that is using these local
variables instead of these private ones
right here so again any time you want to
use the variables in your method instead
of the variables outside your method if
they're named the same thing you need to
use the this keyword and that says
alright use these ones right here or use
this one's not here that doesn't even
make sense but you know what I mean use
them locally instead of far apart so
again it's easier just to see and play
around with it and once you do you're
going to understand what this means
Wow it's like a little joke and anyways
I hope you understand at least a little
bit in the next tutorials I promise I'll
be clearing the software is kind of
confusing right now but um keep an eye
out for my next tutorials don't forget
subscribe and I'll see you next time