Back-End Programming Exam > Back-End Programming Videos > Java Programming Fundamentals: For Beginners > Java Programming Tutorial - 65 - The Final Check Box Program
Java Programming Tutorial - 65 - The Final Check Box Program Video Lecture | Java Programming Fundamentals: For Beginners - Back-End Programming
FAQs on Java Programming Tutorial - 65 - The Final Check Box Program Video Lecture - Java Programming Fundamentals: For Beginners - Back-End Programming
| 1. What is the purpose of the final keyword in Java programming? |  |
Ans. The final keyword in Java is used to apply restrictions on classes, methods, and variables. When a class is declared as final, it cannot be inherited by other classes. Similarly, when a method is declared as final, it cannot be overridden by subclasses. Finally, when a variable is declared as final, its value cannot be changed once assigned.
| 2. How can we prevent a class from being subclassed in Java? | |
Ans. To prevent a class from being subclassed in Java, we can declare it as final. By using the final keyword before the class declaration, we restrict other classes from inheriting from it. This ensures that the final class cannot be extended or subclassed.
| 3. What is the purpose of the final keyword in the context of variables? | |
Ans. In the context of variables, the final keyword in Java ensures that the variable's value cannot be changed once assigned. Once a variable is declared as final, it becomes a constant and its value remains constant throughout the program. This is particularly useful when we want to define variables with constant values that should not be modified.
| 4. Can we declare a method as final and static at the same time in Java? | |
Ans. Yes, it is possible to declare a method as final and static at the same time in Java. When a method is declared as final, it cannot be overridden by subclasses. On the other hand, when a method is declared as static, it belongs to the class rather than an instance of the class. Combining both final and static keywords in a method declaration ensures that the method cannot be overridden and can be accessed without creating an instance of the class.
| 5. How does the final keyword affect performance in Java programming? | |
Ans. The final keyword in Java does not have a significant impact on performance. The main purpose of the final keyword is to provide immutability and prevent certain modifications in classes, methods, and variables. While there might be slight overhead in accessing final variables compared to regular variables, the difference is usually negligible. In general, the use of the final keyword is more focused on code correctness and design rather than performance optimization.
Text Transcript from Video
what's up guys welcome to your 65th Java
tutorial and in this tutorial we're
going to be building a new class to
handle the events when both of our check
boxes are checked so let's go ahead and
make a new class called handler class to
do just this
we'll go private class name it handler
class there we go get eventually
implements I got a type so EMP
implements item listener there we go now
what this does pretty much is a class
that implements item listener and what
implements mean is we get to use all the
methods from item listener but we're
making a promised item listener item
listener says all right here here's what
would happen if they're having a
conversation item listener BIC all right
you want to inherit from me fine you can
but promise if you implement from me
you have to overwrite each one of my
classes so look at this it says the type
hand handler class must implement the
inherited abstract method
so there's abstract methods in item
listener that we need to overwrite
pretty much lucky for us there's only
one method in item listener not very big
class and this method is called item
state changed so let's go ahead and
overwrite this favorite right now so
public void item state change right like
that make sure you spell it right if not
you're going to have some problems and
the parameter it takes here is the item
event event object so what's going on
pretty much is this every time you click
one of these checkboxes essentially
attach them to item listener something
calls an item event occurs or pretty
much an event occurs now what we can do
with this event is add some
functionality to it and it can be
handled by an item listener object which
we created so now whenever since this
item listener is listened
linked to this bold box whenever an item
event occurs it's going to run whatever
is in here so let's go ahead and make
some code to put in here first of all
we're going to want font name it fun
instead of equal to null and this is
pretty much just going to store the font
that we're going to change so what we
want to do is say all right if you click
the bold box we want to bold if you
click the italic box we want the font
italics if you click the bold box and
the italic box we want to bold and
italics if nothing's clicked just have
plain font so let's go ahead and ferd
right if bold box dot and the thingy
rate is is selected just like that and
this is built in method to show if it's
checked or not so if bold box is
selected and let me find it and it's out
what a name italic box
dot is selected then what do we want to
do well let's go ahead and change that
font equal to new font and we're going
to be doing a lot of copy and pasting
after this we want to change it to new
font first of all we want to make it
serif just like before I want to take
that font and make it bold and actually
we need that all in caps I forgot and we
also want to take that font make it
italic and then we want the size to be
14
so get on my way house so what this
means if you press the bold box and the
italic box if both of them are checked
then we want to change the font to bold
and italics so what other options do we
have here whoa we have else if we can
also have an option that if only the
bolt box is selected so let me tighten
that up so actually we can just go ahead
and copy this little too easy so else if
only the bold box is selected then what
do we want to do we want to take that
font and set it equal to new font
and we probably copy this my equal serve
bold copy what did I copy there we go
too easy so if only the bulb box
selected then font equals serif bold and
then the size of 14 so now let's go
ahead and make another else if for only
if the italics is selected so copy we're
getting real lazy here but really
efficient how awesome is that
italics or is it named italic box there
we go
it's selected then we want to change the
font to font italic so now we only have
one other option if it runs through and
sees that if bold is selected in italic
is selected nope if both selected note
if italics is selected nope else this
only else is going to occur if nothing
is selected so what do you want to do
want to do the font and set it equal to
new font and I guess I won't copy and
paste it this time first its serif and
the rest is font up plain and of course
we want to size 14s though so now well
looks like we're good to go and the last
thing we have to do now that we actually
change that font we actually need to set
the font so in our text field we need to
set font equal to that font that we just
changed so this pretty much says alright
depending on what you selected I'm going
to style the font a certain way and then
at the end want to test for all the
styles it says alright I'm pretty much
just going to set it on the screen right
now so now I have this from the last
tutorial which you guys can see it
pretty much just makes a new window on
the screen puts a function on the window
so you can actually close it size for
that window and makes that window
visible so now if we run this and click
OK we go ahead and we got this thing
right here and I promise you to change
that size but this is good now you see
when you click Bowl with the sentence
bolts
when you click italics it italicizes to
if you unclick bold
just as only italics and not bold and if
you uncheck them both it's back to
normal now let me give you quiet guys a
real quick walk through one more time of
how this works
ah take a deep breath you guys ready
good we pretty much made three variables
on screen to hold the text field the
bold box and the italic box in our
constructor we set the title in the
layout nothing new we pretty much added
text field bold box and italic box to
the screen and then we created a handler
class to handle these events
now again anytime you click one of these
boxes something called an item event
occurs now this can be handled by
something called an item listener object
so that's why we needed to link this
object to this class then once we do
that we can handle the events using a
method called item stay changed now this
automatically runs well just like I told
you before and what we did pretty much
is we pretty much had a variable called
font to stylize the font right here here
here and here and then we pretty much
once we found our style depending on
what was checked we set it to the screen
and then we just ran our program made a
window good to go so that's your quick
tutorial on these are called state boxes
because they maintain a state like when
you click them right here I'll show you
why when you click them they stay like
that so that's called maintaining a
state so that's it for this story thank
you guys for watching and next tutorial
we'll be going over more gooeys and
we'll be eventually making this box
pretty effing sweet right now it doesn't
do a whole lot but you know it will oh
and another thing
that if you follow my channel you know
that I give away prizes sometime I am
waiting for prizes to come in the mail
now and it will be the best giveaway I
had so far so just a little tip for you
guys who actually stuck through this
tutorial and watched all nice little
surprised
don't tell anyone else so trust me when
I get my prizes it should be like next
week or something they're going to be
the best giveaways ever so you know
something to look forward to but for now
thank you guys for watching don't forget
to subscribe and I'll see you next
tutorial
tutorial and in this tutorial we're
going to be building a new class to
handle the events when both of our check
boxes are checked so let's go ahead and
make a new class called handler class to
do just this
we'll go private class name it handler
class there we go get eventually
implements I got a type so EMP
implements item listener there we go now
what this does pretty much is a class
that implements item listener and what
implements mean is we get to use all the
methods from item listener but we're
making a promised item listener item
listener says all right here here's what
would happen if they're having a
conversation item listener BIC all right
you want to inherit from me fine you can
but promise if you implement from me
you have to overwrite each one of my
classes so look at this it says the type
hand handler class must implement the
inherited abstract method
so there's abstract methods in item
listener that we need to overwrite
pretty much lucky for us there's only
one method in item listener not very big
class and this method is called item
state changed so let's go ahead and
overwrite this favorite right now so
public void item state change right like
that make sure you spell it right if not
you're going to have some problems and
the parameter it takes here is the item
event event object so what's going on
pretty much is this every time you click
one of these checkboxes essentially
attach them to item listener something
calls an item event occurs or pretty
much an event occurs now what we can do
with this event is add some
functionality to it and it can be
handled by an item listener object which
we created so now whenever since this
item listener is listened
linked to this bold box whenever an item
event occurs it's going to run whatever
is in here so let's go ahead and make
some code to put in here first of all
we're going to want font name it fun
instead of equal to null and this is
pretty much just going to store the font
that we're going to change so what we
want to do is say all right if you click
the bold box we want to bold if you
click the italic box we want the font
italics if you click the bold box and
the italic box we want to bold and
italics if nothing's clicked just have
plain font so let's go ahead and ferd
right if bold box dot and the thingy
rate is is selected just like that and
this is built in method to show if it's
checked or not so if bold box is
selected and let me find it and it's out
what a name italic box
dot is selected then what do we want to
do well let's go ahead and change that
font equal to new font and we're going
to be doing a lot of copy and pasting
after this we want to change it to new
font first of all we want to make it
serif just like before I want to take
that font and make it bold and actually
we need that all in caps I forgot and we
also want to take that font make it
italic and then we want the size to be
14
so get on my way house so what this
means if you press the bold box and the
italic box if both of them are checked
then we want to change the font to bold
and italics so what other options do we
have here whoa we have else if we can
also have an option that if only the
bolt box is selected so let me tighten
that up so actually we can just go ahead
and copy this little too easy so else if
only the bold box is selected then what
do we want to do we want to take that
font and set it equal to new font
and we probably copy this my equal serve
bold copy what did I copy there we go
too easy so if only the bulb box
selected then font equals serif bold and
then the size of 14 so now let's go
ahead and make another else if for only
if the italics is selected so copy we're
getting real lazy here but really
efficient how awesome is that
italics or is it named italic box there
we go
it's selected then we want to change the
font to font italic so now we only have
one other option if it runs through and
sees that if bold is selected in italic
is selected nope if both selected note
if italics is selected nope else this
only else is going to occur if nothing
is selected so what do you want to do
want to do the font and set it equal to
new font and I guess I won't copy and
paste it this time first its serif and
the rest is font up plain and of course
we want to size 14s though so now well
looks like we're good to go and the last
thing we have to do now that we actually
change that font we actually need to set
the font so in our text field we need to
set font equal to that font that we just
changed so this pretty much says alright
depending on what you selected I'm going
to style the font a certain way and then
at the end want to test for all the
styles it says alright I'm pretty much
just going to set it on the screen right
now so now I have this from the last
tutorial which you guys can see it
pretty much just makes a new window on
the screen puts a function on the window
so you can actually close it size for
that window and makes that window
visible so now if we run this and click
OK we go ahead and we got this thing
right here and I promise you to change
that size but this is good now you see
when you click Bowl with the sentence
bolts
when you click italics it italicizes to
if you unclick bold
just as only italics and not bold and if
you uncheck them both it's back to
normal now let me give you quiet guys a
real quick walk through one more time of
how this works
ah take a deep breath you guys ready
good we pretty much made three variables
on screen to hold the text field the
bold box and the italic box in our
constructor we set the title in the
layout nothing new we pretty much added
text field bold box and italic box to
the screen and then we created a handler
class to handle these events
now again anytime you click one of these
boxes something called an item event
occurs now this can be handled by
something called an item listener object
so that's why we needed to link this
object to this class then once we do
that we can handle the events using a
method called item stay changed now this
automatically runs well just like I told
you before and what we did pretty much
is we pretty much had a variable called
font to stylize the font right here here
here and here and then we pretty much
once we found our style depending on
what was checked we set it to the screen
and then we just ran our program made a
window good to go so that's your quick
tutorial on these are called state boxes
because they maintain a state like when
you click them right here I'll show you
why when you click them they stay like
that so that's called maintaining a
state so that's it for this story thank
you guys for watching and next tutorial
we'll be going over more gooeys and
we'll be eventually making this box
pretty effing sweet right now it doesn't
do a whole lot but you know it will oh
and another thing
that if you follow my channel you know
that I give away prizes sometime I am
waiting for prizes to come in the mail
now and it will be the best giveaway I
had so far so just a little tip for you
guys who actually stuck through this
tutorial and watched all nice little
surprised
don't tell anyone else so trust me when
I get my prizes it should be like next
week or something they're going to be
the best giveaways ever so you know
something to look forward to but for now
thank you guys for watching don't forget
to subscribe and I'll see you next
tutorial
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Nov 24, 2024 Last updated |
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