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Let's not continue without them all earlier we have seen how an exception can be generated on how it

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can be handled it's not on a couple of more things first is about having more than one exception in

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the last.

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OK.

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So trust Roesgen how multiple exceptions.

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So we will look at that.

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And the second is that an exception object can be referenced.

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Polymorphically.

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OK that's possible.

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And that's because an exception is basically an object.

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OK.

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So we will also look at.

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So let's just go ahead and extend the cord.

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Destination is equal to one so we said that if destination is Vaun it means that we want to pass the

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date up programmatically to the park nursery.

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So it's OK.

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So that's what we're going to do.

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And if the partnership is done that is it is unreachable then it would throw an exception called us

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Iowa exception OK which is also from the Gelada art IO package even file not found exception was from

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the Java dot IO package but that's an exceptional situation.

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Typically you don't have so much going on often.

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So that's an exceptional situation.

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And when that happens we need to raise an exception.

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So let's just do that let's just throw new your exception.

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OK.

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Now we need to import this Naga second exception as we know that it needs to be mentioned here.

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So let's have it here be a good Let's go back here to exceptions Demel now send mattered also needs

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to handle that exception.

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OK so when behavior it shows four options let's pick the second one which says I got glass to surrounding

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you so there is a song on and try on we want to get Gutch glossier.

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OK let's do the now and start off here.

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So we have Iowa exception now.

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So let's put a print statement here.

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Because in the catch block we are going to how exception handling code.

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And for now this is our exception handling course so this is how we recover.

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Saw this you are just saying connecting to a different server.

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Ok so that's how we're going to recover from this exception.

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So let's just go hard and change this to one here.

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Now and it's just you're on it.

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So we are inside main inside share inside San and then an exception was generated and then we and then

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the controller came here into Iowa exception under sprinting connecting to a different server.

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And once that is done and share is printed on this particular matter has popped off the stock.

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And then finally and off Manus Bernard Here.

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So that's multiple exceptions.

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So you can have it within the glass you can have multiple exceptions.

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So that's the first thing.

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And the second thing is so we know how we know how to objects here exception objects are the exception

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objects can be referenced polymorphically.

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Now in this case file not an exception is actually a supperless off Iowa exception.

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OK.

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So file not for an exception can be referenced using IO exception.

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OK so that's possible.

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So we are going to reference it polymorphically on what that means is we don't need both of them here

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so we can just remove this year and it will be polymorphically referenced by Iowa exception so you don't

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see any compilation error.

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Now the same can be done here also.

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So we don't need to catch blocks here.

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So that's just common default and let's change it back to zero soil file not for an exception is done

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record but it will be caught inside an exception handler which has no exception.

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OK so let's just go ahead and run this now you can see that we are inside this exception Rocklynne file

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not for an exception has been generated.

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It's generated because we are passing zero but we shouldn't be doing this often.

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In this case we shouldn't be doing it because you'll see it's a file not found exception.

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Unbe are saying that we are going to get a different server.

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So the court has to be specific defined not for an exception.

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So in this case.

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But I like ception objects and I find not for exceptions both of them have the same put it over the

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court and we don't want to do that.

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So sometimes it is fine.

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But generally you would want to how specific to cover the court.

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So let's just change it back here.

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So this is how it needs to be k so that very well how specific error handling Goertz not and another

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thing is here file not found exception is a subclass of this.

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So these exception handlers should be placed from Subclass to words superclass So if a subclass exception

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handler should come before a gross exception handler.

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Otherwise we get a compiler that.

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Let's actually try that k now you'll see that as a compilation error on it says unreachable catch block

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for filing for an exception.

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It is already hundred by the catch block for Iowa exception.

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So you cannot do that.

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So let's just say control-C.

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So this is how it should be.

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And so that's about polymorphically referencing them.

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Now you can also how other exceptions like for example both fighting not for an exception are no exception

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are subclasses of this classical exception so you can also have dark and exception is actually a direct

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supperless of true love.

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So you can also have trouble here.

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So both of these are possible.

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OK so you can do that.

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So that's all because off exception objects can be referenced polymorphically as an exception an exception

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is basically an object.

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OK.

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And another thing is we said that it goes from subclassed to supercross here.

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But let's say if the exceptions are siblings.

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As long as they don't how would the exception clauses do not have a superclass oppressive relationship

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.

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Then we could we can have them in any order.

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OK.

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Only thing is if they have a supercross up close relationship on it only then the supperless should

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come before supercross.

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OK so as long as it's within the exception inheritance tree that starts with the Crucible as long as

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they are not in the same inheritance but we are good so they can be in any in any order.

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And so that's about it.

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Now the cool thing about this whole exception handling mechanism is all you are exception and exception

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handling code is one place.

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OK so you don't it's not scattered across the hall and outsource scored and then a class.

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So it's all in one place of Fard you know for the gross statements.

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So you can you can always you know with a quick glance you can you you know what kind of exceptions

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can be generated.

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OK so that's one nice thing.

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And the second thing is compiler is actually forcing us to handle the exceptions.

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OK.

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And it is not making the programmer to handle it as an afterthought if it is like an afterthought.

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Then the programmer would be lazy and really not might and most likely not provide the exception handling

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code because he or she might forget about it.

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So that that would lead to for a trial record.

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So because handling except exceptions is basically an exception in situations happen in exceptional

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situations on computer wants us to handle it.

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OK.

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Now sometimes programmers how something like this.

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Normally it is by convention a lot of people use only exception procedure but it is.

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But as we mentioned earlier we need better re how specific exception process.

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But when they do how sometimes they're just don't provide any body within the catch block you know they're

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just how empty balances on that is also not good.

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So so in a way you're kind of cheating it cheating the compiler itself.

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So that's not good.

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And there is an item specific to that it would be to look at that later but it mainly says that we need

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to have some kind of audit already called but we will look at that item later.

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So the compiler is basically checking that the truest clause includes the exceptions here.

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If you have some kind of a troll statement here if you're throwing some exceptions it is ensuring that

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we how it checks that it checks that the exception is specified here in their declaration.

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And it also checks that the exception is caught somewhere.

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OK.

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So there is an exception handler.

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So it's going to check it's going to do that kind of a checking for these exceptions.

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And for that reason all these exception classes are referred to as checked exceptions as they're being

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checked by the compiler.

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So what that means is there are also other types of exceptions which are not checked by compiler.

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So which means that you can throw an exception but you need not specified them in the declaration.

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Similarly you need not catch them also.

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So there is no option on it to catch them.

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So those are all different types of exceptions on there since they're not being checked by the compiler

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that cardless unchecked exceptions.

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OK.

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Undoctored that is something that we would look at in the next lesson.

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OK.

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So that's about it for now.

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Thank you.

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And happy coding and I'll see you in the next lesson.