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That's not it's because final variables when that typically as a program it's a good value stored in

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variables keep changing.

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In fact the term variable itself implies that it is something whose value can be changed.

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But sometimes we may wonder why you never change that is we may want why you remain constant or fixed

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once initialized for example there may be a variable representing maximum number of courses that a student

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can register for.

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In this case you've got the maximum number of courses to be fixed.

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For this you would declare the variable as a final variable that is you would use a modifier Feiner

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in the variable declaration recall that we briefly discussed it in the switch statement Allison there

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we have to use a type of final variable called constant variable in the next lesson vividly defined

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constant variables in a more formal way.

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In fact most of the time constant variables are what we use not the final keyword can also be used with

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classes and mentors.

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But we will look at that later.

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For now let's focus only on its use with variables so the term final simply implies that something cannot

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be changed.

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That is it is final so for variables value should be final.

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That is it shouldn't change once initialized then it needs to be marked with a key word.

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Final.

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And here is an example.

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It's available pie from the math class.

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It is declared as final as it's valued £3 1:04 should never be changed.

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So fine and reliable basically implies constant if it is used with a primitive variable then the value

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can never be changed.

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But here's the interesting thing.

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If it is used with a reference variable then the reference is constant.

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There is a reference always points to the object.

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It was initialized but that is it can be reassigned another object.

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However.

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And of that object can be changed.

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So you should keep that in mind.

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Don't be under the assumption that object content cannot be changed just because it is marked does.

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Final disciplines the arts also as arts are objects so that confidence can be changed.

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But we cannot rely on a new or a good or variable find out what it will do not get a default value.

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The reason for that is a final variable gets a default value and is initialized once again.

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Let's say in a constructor using one of its parameters then we are violating its core definition.

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So when we say final we want the variables value to remain fixed forever next final key word can be

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used with any of these three variables instance local or static let's look at final instance variables

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once initialized a final instance where rebels value can not be changed for the life of the object we

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know that a final variable does not get a default value since we are talking about final instance variables

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.

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The rule is that there must be initialized either in the declaration itself or in the constructor or

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in that instance initializer.

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Otherwise we get a compiler error.

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So you can do even initializer in a method.

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That's because if you could initialize it in a method and that method is not invoked then the variable

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is never initialized.

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In that is we could very likely run into an urge when statements involving that variable gets executed

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so it needs to be initialized in one of these three places nodded If declaration LAXON an equalizer

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and is initialised later in a constructor or in an initial as a block then the final variable is referred

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to as blank 1A non-X extra a student example to include a final instance variable OK here's a student

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class and here we have the student test class and we know that regear student instances from the Student

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class and here we're creating three student instances and we're passing the state by invoking the constructor

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and the state involves the ID name and gender.

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And as you can see here the idea is being set manually by us but in real world such ideas are generated

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automatically by the system itself.

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And let's also do that in this Demel.

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OK so let's order Jondrette IDs in this demo.

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OK so two things need to happen here.

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One is the I.D. that is generated should be unique to each student.

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OK.

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And for that we will create a static variable in the Student class.

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OK.

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And the next thing is once the ID is set in an instance that value should not be changed.

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So within that object we should not be able to change the ID.

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So it needs to be.

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It needs to be fixed for the life of the object.

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And we know that we can use in final instance where the bill for that.

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OK so let's just go ahead and do that.

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Crusting Let's come on this art.

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Let me also remove this since we don't have to set it manually anymore.

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We can set it.

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It gets auto generated.

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So let's just remove this OK.

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It's going to student class fostering is let's

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change the constructor that's the parameter.

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And it's also remolded statement.

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It's going to get top let's introduce the static variable engendered the unique ID sins it's going to

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initialiser ID let's call it as ID initialiser initialize it to Dowson and here is the ID field.

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And we need to make it fun.

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So now it's a final instance OK.

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So let's just go ahead and compile this notice variable ID might not have been initialized right.

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So we said that the ID field if final variable will not get a default value and it needs to be initialized

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either in the declaration statement or in the constructor or in one of the initializer blocks.

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So since we dont have any sheilas or block so it needs to be done here or here.

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So let's just go ahead and do it here.

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Let's say ID equals plus plus ID initialiser.

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OK.

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So the first student instance will get an idea of tolls or non-blood because it's we have initialized

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it 2000 here in the top the second 2002 it's also have this pen statement.

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We are just printing the ID of the main name is basically the student mean ease.

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This is the I-T.

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So just a print statement there.

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So let's just go ahead and compile me answer on this

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as you can see for each student it's bending and ideas and ideas are generated and it's also unique

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.

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OK.

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So that's a final instance variable.

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OK.

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Now we also said that we cannot re-initialize a final variable.

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So let's just try to do that here equals cease and desist search something else it doesn't matter.

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So let's just compiler and it just cannot assign a value to final video ID.

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OK.

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So since it's final You cannot do this you can only initialize it once on once initialized.

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It's fixed.

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So that's about it.

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So that's the final instance variable.

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And let's just head back to the sleights next is find a local variables under this straightforward once

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initialized in a block that's better than the final local variables value cannot be changed for the

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rest of the block.

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Hit as an example that the method that I'm told is fine.

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So trying to change the value really to compiler next is final key word used with tactic really because

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we know the Arctic really about our blossomy rivers once initialized a final start.

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But it is constant regardless of any number of objects created for example here is a final static variable

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.

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Karl Marx underscored a value which is defined in a class called integer from the dollar doglike package

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.

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So no matter how many instances we create of this class Maximus discord you will always have this constant

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value like final instance variables final static variables must be initialized either in declaration

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or self or in the static initial as a block.

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I'd always get a compiler error not come into naming convention final static variable should be in all

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caps with an underscore separating the words.

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Here's an example from collections class which is from the Jawa got Udal package.

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So if you want to declare constant values across your entire system you can declare them as final static

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So that's an introduction to final variables.

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Next we will look at constant variables which are a type of final variables