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So we work with our department quite a bit here and I created my accounting department.

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Now for the application we're building we might need departments of course but we might need more information

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for the specific types of departments we might have an I.T. department which has an I.D. which has a

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name which has employees but which also has administrators something which only the I.T. Department

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has for example we might have the accounting department which might all have an I.D. or a name and employees

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but it might also have let's say reports in Israel for reports it degenerated and so on.

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So we might have some base properties and also methods which all departments should have.

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But then we might have specialized workings of these apartments with their own specific properties and

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methods which only that the part that might have an inheritance can help us implement something like

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this.

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So how can we utilize inheritance here.

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Well we have our class department now let's create these specialized departments.

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So here we could have a class I.T. department and in this class here I want to utilize the name and

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the I.D. and the employees of the general department.

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But I want to add my own features.

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Now we can inherit the department class by using the extensions keyword here.

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And then the class we want to inherit.

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In this case that's department.

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Now important you can only inherited from one class so you can't inherit from multiple classes.

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If you would need that.

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So now you're inheriting from department.

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And one consequence is that if I now create an I.T. department here I indeed can call it like this with

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this kind of constructor.

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Even though the I.T. Department class is empty if we save that we indeed see it works.

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Ask before because when we inherit from another class the class which inherits automatically gets everything

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the base class department in this case has including its constructor.

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So as long as we don't add a dedicated constructor Ford is inherited class so Ford to subclass the base

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classes constructor.

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So this constructor is automatically used when we instantiate our subclass.

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So we in the end magically call the base class constructor with the arguments per passenger.

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Now we can add our own constructor though by adding constructor here in I.T. department.

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And now you see I'm getting errors.

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For one we now of course should accept the data we're getting here though we could argue the name should

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not be something we need to pass in here and it shouldn't also be accounting but instead here the name

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of the department since it's the I.T. Department class can always be I.T..

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I still want to accept my I.D. though.

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But now I want to essentially forward that just like you fixed name I.T. to the constructor of department

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and for that we have a special keyword we we can and in this case we have to use and that's super whenever

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you add your own constructor in a class that inherits from a number of class you have to add super Indian

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heritage class and you have to execute it like a function super here calls the constructor of the base

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class.

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So department's constructor in this case and now they are first super takes the arguments of the parent

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class constructor the I.D. and the name.

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So here it can forward I.D..

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So I.D. which I'm getting here is just passed to super.

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And it can hard code a value for the name like a T.

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So this will now call the constructor of the base class from inside the subclass not important.

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You have to call super first in your constructor before you do anything with the this keyword.

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So if you plan on assigning any other special properties here you have to do that after calling Super.

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And indeed I want to add my own special properties here.

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We could add our admins here let's say as a private whereas a public actually as a public property admins

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and that should be an array of strings let's say.

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Well then I don't want to forward this to my base class because the department class doesn't want any

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administrator data.

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Instead I want to store it is in a property of I.T. department.

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So here we can then add admins as a field which takes a couple of administrators and store admins in

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there or because I'm using public and here I'm already using that shortcut where a property of the same

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name will be created and the data we feed into this argument is stored in that automatically created

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property still to make it clear that super has to be called first.

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I'll take the longer route add Adam Edmonds here like that and that here say this dot admins equals

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admins.

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Again the shortcut would be shorter.

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I'm doing this here to show and make it really clear that if you are using something that uses the this

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keyword you have to do that after calling Super.

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And with that if we save that I'm getting an error because I'm not passing in any admin so let's do

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that here.

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Max is the only admin I'm passing in here.

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Now we can save that and compiled it without errors.

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And now here indeed we see our department here.

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It now has the name I.T. and if we can so lock the entire department and we may be all the renamed is

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from accounting to I.T. and then console lock I.T. here of course renaming that while it's optional

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just makes more sense given that we're building an I.T. department here now that a console locked entire

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department we indeed see we got admins but we also got employees and everything which I set up in my

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department class here.

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So that's inheritance and action.

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A very useful feature because now of course we can all do create our accounting department here by extending

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department and there we could then add our accounting specific things so we can still use a constructor

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here.

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And now maybe with the shortcut except a couple of reports here which might be a private property and

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then we have ADD report which takes text which should be a string and then we reach out to reports here

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and push text as item into the report and maybe we also have get reports here and there we just console

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lock this reports or we name it print report stage 4.

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Makes more sense and now we would have a very special Where's another department with two methods which

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the pace department doesn't have.

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And with extra property which to base department doesn't have and still we get everything from the base

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department the name which I'll set to accounting here and the I.D. which we all look forward to the

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base department constructor.

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And so with that down there if we create our accounting here with new accounting department we can feed

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in our I.D. and then our reports let's say that's an empty array initially then we can call at report.

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Something went wrong never that good of course in the accounting I guess.

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And then we can also print our reports here like that.

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And with all of that it compiles just fine and we get the reports here and we see the I.T. Department

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for example wouldn't have any reports.

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The accounting department does because of inheritance where we inherit certain features and add our

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own features.