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The very last step is to bulletproof the application, in other words, to make sure the application

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doesn't fail or crash no matter what happens right now, there are many scenarios where an unchecked

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exception could be thrown during the run time and crash the application.

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We can't allow that to happen.

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So let's run the up.

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The first vulnerability in the app is if the user enters a blank movie name.

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The movie constructor is going to throw an illegal argument exception, and as you know by now, if

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we get an unchecked exception, it's our fault and we have to fix it.

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And what we're missing is code that anticipates a scenario where the user may enter a blank name.

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So here will say if name is blank.

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Then we'll print the following message.

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Then we'll restart the loop with continue.

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OK, let's run our code.

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And if we had a blank name, our application handles the response with grace.

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You know what, if I rent a movie?

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Then I'll try to purchase that same movie.

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And the Atheros, an illegal state exception, crashing the app, we cannot allow the user to purchase

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a movie that has already been rented.

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So I'll go back in main.

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And I'm going to check if the movie is rented.

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Wait, how do I do that?

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Right now, we can't we need to declare a method inside Staudt Java that returns a movie based on a

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name.

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So public movie get movie.

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It's going to take one parameter string name.

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I'm going to create a loop that runs through the size of the array list.

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And will say if movies.

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We'll get the movie at the request index.

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doGet name will check if it equals the name being Pastan.

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Then we're going to return the movie object at that inducts.

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Otherwise, we're going to return now.

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Now, back in Maine, I can get the movie the user is interested in iStore get movie.

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We need to check if it's not available.

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And if that's the case, will print the following message.

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Movie is not available for purchase and restart the while loop.

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OK, let's test this out.

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I'm going to rent a movie.

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Try to purchase that same movie.

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And the application responds with Grace, it's not available for purchase.

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Now, I'm going to try to purchase another movie, but I'm going to type a movie that isn't on their.

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We'll say Django.

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And it crashes null pointer exception.

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The issue is that the function we just added returns and null if it can't find the movie.

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And trying to dot syntax from a nul is going to result in a null pointer exception.

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So we need to handle that as well.

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So here, instead of checking if the name is blank, I can just make the condition check if the movie

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they added doesn't exist.

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This condition would account for everything.

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Kate running the app.

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I'll put a movie that doesn't exist in the collection, we're a good.

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I'm going to put a blank movie, we're good.

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Our condition is perfect.

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And with this final line of code, I'm proud to say that we're all finished no matter what we do, the

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application is going to respond with Grace and it's working really well, just like that.

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Our application is bulletproof.

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No matter what the user throws at us, the application is free of bugs and it's never going to crash.

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It can process any input and respond with grace.

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In the end, exception handling, which involves catching checked exceptions and fixing unchecked exceptions,

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is the key to building bulletproof applications.