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There are two more classes we need to write up in this video.

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We'll do the shopping cart.

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The shopping cart is identified by the items that it carries and the number of items can increase or

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decrease in the shopping cart.

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So right there, we know we need to make an array list that can store item objects.

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And as always, if a class has failed, you need to apply the big three steps, you need to take instructor,

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a getter and a setter.

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The instructor is public shares the same name as a class.

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And it receives no parameters because in the beginning, your card is going to be empty, we're just

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going to set the field equal to a new era list that can store item objects.

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OK, now we want to get her there, receives a one parameter.

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The index of the item object they're trying to access.

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And this letter is going to return a new copy of the item object at the request that inducts.

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Now, we went out a centre that receives two parameters.

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The index of the element you want to update.

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And an item object that we're going to update the element with.

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Then we're going to get the element at the requested index.

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And set it equal to a new copy of the item object being Pastan.

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And that's all for the big three steps, if you feel like it's getting repetitive, then that's good.

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It means you're getting the hang of it.

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Now we're going to add actions.

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One thing we can do is add an item to the card.

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So all credit boolean method named ADD it receives one parameter and item object.

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And the duck comment tells us we can add an item only if it wasn't already added, I'm going to ignore

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this condition for now.

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I'll come back to it at the end.

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For now, I'm just going to add the item to the items list.

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And return true.

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The next action that it can perform is to remove an item from a cart.

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This method is void called remove, and it receives one parameter, the name of the item you want to

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remove.

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So what we'll do is create a far loop that runs through the size of the array list.

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And inside the loop, we're going to get the item object at every index I.

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We'll get the name field of that item and we'll check if it equals the name of the item, though, as

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Pastan.

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And if that's the case, then we're going to remove that item from the array list.

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The last method is check out this one return to string that resembles a receipt.

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And the receipt needs to include three things, the subtotal, which means the price before tax, the

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tax they have to pay and the total.

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And instead of creating three separate variables, I'd rather create an array with ALENKA three.

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And so the idea is that the first element is going to be the subtotal, the second element, the tax

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and the third element is going to be the total.

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So during each run, I'm going to update the first element, the subtotal and add to the price of the

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item inside the cart.

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So that should give us the price of every item before tax, the tax rate is 13 percent.

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So we'll set the second element equal to the first one.

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Times point one three.

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And now the total is equal to the subtotal plus the tax, so we'll set the third element equal to the

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subtotal plus tax.

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All right, now we have the total subtotal end tax so we can return a receipt, just copy over the format

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from the article.

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And replace the placeholder is where we need to.

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Kate, now our final task before we can test our code is add it to string method that returns a nicely

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formatted string of every item inside the cart.

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As always, public string to string.

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I'm going to create a string named temp for temporary.

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It's going to be an empty string for now and we'll just return it's.

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First, don't create a loop that runs through the size of the array list.

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And during each run, I'm going to get the two string of the item object at the index eye and I'm going

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to add the string to the temp variable that we're returning.

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And after adding the two string of an item, I'm only going to add one line to separate it from the

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next two string that gets added.

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OK, now we're going to test our code before we do anything else.

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I'll have to create a shopping cart object inside Main.

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I'm going to add four items to the shopping cart, so I'll go back to the article, I'll copy them over.

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And print the cards.

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And by printing the cart, it prints a nicely formatted string of every item inside the cart, but it

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seems we added the salary twice for our purposes.

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We only want to allow the user to put one of each item.

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We can't have any duplicates.

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Well, thankfully, every aerialist has a contained method, the method receives an object, it returns

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true if one of the elements inside the array list equals the object they were passing in.

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So what I'm going to do is check if the items array list already contains the item being Pastan.

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Then I'm going to return false.

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Otherwise, the item will get added and will return true.

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And now you might think, OK, we're good contains is going to behave exactly like we want it to.

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It's going to check if the array list already contains an object before adding it.

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Yeah, let's run the code and see what happens.

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First, it adds the celery, OK, that's fine.

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But then we get the exact same Sellery object, its fields are identical to the one already in the array

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list, the array list and our eyes already contains that object.

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But it gets added anyway, so why isn't this condition evaluating to true, why doesn't it recognize

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that the array list already contains a salary object?

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The short answer is we need to help the contains method achieve its goal.

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So before we move on to part four, you need to learn about the equals method.