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Welcome back in this video, we're going to look at the race and race, as we saw earlier, allow us

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to store multiple pieces of data in one variable, so to speak.

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So let's create our first rate for the integer type and also see the different ways we can create an

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array.

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So first of all, I'm going to use the keyword volume and I'm going to call this variable numbers and

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that will be of type entry.

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OK, so using in-tray and then I need to use this method called int array of where I can then assign

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values.

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So int values and multiple ones so far are elements of Typekit, which means I can just go ahead and

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just add a couple of numbers separated with a comma.

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So I have these values here one, two six.

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So that's one way of creating it.

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But then because of type inference, we can just go ahead and use a simpler approach where we can get

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rid of this in-tray here entirely.

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So let me copy that.

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And here we can get rid of this part.

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Therefore, I need to comment this out.

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So because we are using int array of numbers knows that it should be an array of integers.

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So that's type inference here.

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We don't need to specifically state that it's going to be off type into array.

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So by the way, there is an even simpler way of doing it.

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So another way of using type inference, and I'm going to again copy the line of code comment the other

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way out.

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And by the way, all of them are valid, right?

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These are just more descriptive.

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So they are really, say, throwing to the point what's going on here?

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And then we have this one where we don't even need to say that it's an entry, which is to say that

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it's an array of.

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So now let's go ahead and print an array.

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We can just go ahead and say print numbers, and let's run this real quick.

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Then we will see that it just prints this information for us.

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So we would have expected to get the numbers here, right?

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But what we're getting is actually this year.

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So we are getting the address of the array, which is where it is stored in memory.

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This is because we cannot just print a race with the print method.

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We will need to use a utility method provided in Scotland for that purpose.

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So what we can do is we can use numbers and that's a cool thing of the array off here.

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So this is an array now and we can just go ahead and use a method called content.

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To string.

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So what that will do is it will transfer the content into a string, convert it for us, and then we

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can now display the numbers and you can see now it just says, OK, this is an array, and that's why

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we have those square brackets here.

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One two three four five six.

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OK, so now we can see the values in the right format.

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So now let's traverse through in a way, meaning go through the items of the array and print them individually.

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So that would be a different approach.

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Let's look at it.

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And I'm going to simplify the code here, and the easiest way to do it is to use a for loop where I'm

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just going to say an element inside of numbers.

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And this element is just a variable name.

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You could have called it I or whatever you want it.

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And I'm just going to say the element in numbers is what I want to print.

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So let's print elements here.

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So what's happening now is that it goes through these numbers array.

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And for every single item starting from the 1st, it will store that in element.

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In the first iteration and the second iteration, it will store the two in element.

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In the third iteration, it will store to three an element and so forth.

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So it's going to go through all the numbers inside of this numbers array and we'll store them in element

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and then print them out and then go to the next number printed out, go to the next number and so forth.

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So here we're just printing, but you could do whatever you want to do with that particular element.

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You could modify it and store it somewhere else.

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You could display it and so forth.

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So we're just going to display on the console using a print state and you can see one, two, three,

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four, five and six.

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So all the numbers that are inside of numbers are now being displayed.

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So now let's actually do a modification here, so I'm just going to go ahead and add an empty space

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here and add two to it.

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So here plus two, for example.

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Now, if I run that, I will see that it will just display one plus two, two plus two and so forth,

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it's not doing the actual calculation.

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Do you recall how to actually do the calculation here when we were using string manipulation here?

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What we need to add the curly brackets around it.

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So let's run it again.

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And now it will add the number to the element.

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But that by itself will not change the numbers itself.

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OK, so if we were to now do the same thing once again after that and we print out numbers without adding

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the two to it, therefore we don't need to have those brackets.

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Let's run this code and you will see that our numbers are not actually impacted.

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So three four five six seven eight.

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But the actual numbers are still one two three four five.

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So we didn't change the value itself.

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We just displayed it, so we didn't overwrite it.

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So now let's modify a value in the array, and since arrays are indexed based on starts counting from

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zero, it means a position of one in our array is going to be zero.

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The index of two or the position of two will be one and so forth.

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It's a little confusing.

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But let's look at it in order to understand it a little better.

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So I'm going to get rid of this for loop here.

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I'm going to print numbers and now if I want to access a particular item inside of the numbers array,

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I just need to use the square brackets here.

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So if I, for example, want to access index zero, this will give me one.

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Let's test this.

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And you will see that at this place one, in fact, because it starts at index zero, but the first

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entry that we have is one at this position.

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So now let's use Index three, for example, and that will give us the four.

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Let's run it again.

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And here you see four.

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So this has nothing to do with the actual numbers that are in here.

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It just has to do with the position that we are looking at.

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So the index of that array.

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So here, let's say I'm entering five and I get the number at position zero.

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Now it will give me the five instead of the one because that's what is stored at position zero.

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OK, let me go back to one here.

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So now let's modify our arrays a little bit.

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So now let's modify the array a little bit.

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I want to store a different value at position zero, for example, in order to achieve that.

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I just use the name of the variable, which is numbers then are used to square brackets with the index,

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which I want to change, and then I assign the value that I want to assign.

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So in this case, let's say it's position zero.

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I want to use the number six and at position one, I want to use the number five and then four index.

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I'm going to use the number two and finally four index five.

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I'm going to use the one.

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OK, so let's now look at what happened, so first of all, I'm going to print the initial value of

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my numbers and I'm going to call this one initial.

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Values.

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And then used to square or the dollar sign with.

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The round, the bracket surrounding it, like so and then I'm going to print it with that.

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Changed values, so.

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With a new line, by the way, therefore, I'm using the backslash end and then going to call it final

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values.

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OK, so let's run this and see how this has impacted our array here.

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We could see initial values were one two three four five six, and the final values were six five three

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four two one.

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So now, since arrays have a fixed size, we cannot increase the size or try to add a new index since

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we have six values and the index starts from zero to five.

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If we try to add something to numbers at the index seven, for example, this would not work so I can

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get into a bounce out of balance exception doing that.

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So let's say I want to assign two to position seven.

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Let's run this and you see we get an error here, it says exception in thread main array index out of

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bounds exception.

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So Index seven out of bounds for length six.

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So we try to access an index that doesn't exist.

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So the same would even go for Index six because we only have six entries and it starts at zero and goes

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all the way to five.

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So here exception.

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So that main index six out of bounds for length.

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Six.

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Okay, because it starts at zero.

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That's why six is already out of bounds.

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Now we can use the same with the double array.

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So numbers, for example, this would be our array just using the double array keyword off.

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And of course, you could have simplified this the same way.

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And here I'm going to override the double array.

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Like so but then you have to specifically use double numbers, which means you have to add the floating

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point value to them.

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Otherwise, it wouldn't work.

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So you cannot assign an integer to a double array.

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You couldn't see that directly here because we got an error here.

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Otherwise.

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Or you can go ahead and use an array of four days.

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So let's go ahead and use that here.

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So while days will be an array of.

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And you just use Sun, for example.

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Then Monday and you see you separate the entries even if you're using strings each time with a comma.

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So each entry is handed like this inside.

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Of our brackets.

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So then if you want to display it, you would do the same thing as we saw earlier with content string.

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So here I have all of the days of the week and now I'm printing them and.

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This will have not any impact here.

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Let's also get rid of this statement here, and let's just display the days of the week and you see

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Sunday, Monday, Tuesday, Wednesday and so forth.

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We can even go as far as to store entire objects inside of an array.

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So therefore, I'm going to create a small data class outside of this function, also outside of our

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main function here at the bottom, and I'm going to call this one fruit.

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And this fruit will need a name.

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So while name of type string and it will need a price, for example, of type double.

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OK, so that's how the structure of our data class will be.

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And now we can just go ahead and create a fruits list, which will be an array of.

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The different fruits.

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So here we can now create fruit objects of fruit object one will be an apple and it has a price of,

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let's say, a price of two point five dollars or euros and then create another fruit.

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Which will be, for example, great and that will then cost three point five euros per kilo just as

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an example.

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And we can print the fruits in the same way as we would with the days.

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So here this is print fruits with content to string, and let's run it real quick.

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And we can see here we have the fruit named Apple Price two point five and the other fruit grape and

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so forth.

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This will be super useful and we're going to use that quite a bit in the future.

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Now you can also access individual items.

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Of that fruit and printed instead of printing all the fruits content, you can just go ahead and just

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display the fruits name.

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OK, so I could just go ahead and say where the fruit is at which index.

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So here let me use the quotation marks a rounding.

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Basically, I'm saying fruits.

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Give me the index as well.

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And in order to get the index, we of course need to.

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There's a for loop, so for index in roots and then indices.

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This gives me the indexes like so.

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Then inside I would just to print index, so this doesn't give me the fruit itself, but it gives me

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the index of the position of the fruit.

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So here I want to get the name of the fruit at a particular index.

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That would be a weight.

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And.

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Let me add the quotation here as well.

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This is one way to get the indexes, but if you just want to get the fruits, there is an easier way.

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You can just use a follow-up where you go for each individual fruit inside of fruits and you just print

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the fruit name.

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So here you can just go ahead and say fruit dot name.

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And this will give you the fruit name.

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So let's run it.

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And you will see that we now get the fruit names.

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And let me actually get rid of the base here so we can see a little better.

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And we could see Apple and grape, and then Apple is at index zero.

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Rape is index one.

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So this was apple and grape, and this was the indices.

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By the way, you can also have an array which uses multiple different types of data, so here let's

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use this days, for example, and instead of days now we have this little mix up where we use Tuesday

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and then we just assign a numbers like, so it's just a new number.

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And then here we also have a fruit object so we can just go ahead and say fruit apple with a two point

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five price.

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So this would be in a taste, but mix and then this print those as well.

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So here mix that content to string.

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And therefore, let me comment those other parts out, and let's run our quote.

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So you see, we have Sunday, Monday, Tuesday, one to three fruit with the name Apple and price of

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two point five.

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So the beauty about resolve is really that it can hold different types of data.

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And we saw earlier that there are these double arrays, for example, they can only hold doubles and

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interest.

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It can only hold ends.

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There will be more efficient as well as safer.

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So why would you use an interface?

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You can just go ahead and use an array of?

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Well, the idea is that interface are super on point and they can only hold numbers.

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So imagine you get the data from somewhere else.

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And for some reason, the database gave you an integer the position where you would have expected an

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end and then your coat would directly figure it out and you could get away around it.

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Except you could add an exception that would then manage that problem and go about it.

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OK, and that wouldn't be recognized if you have such a mixed array that doesn't care what kind of data

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it has.

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OK, so that's pretty much it for this video.

231
00:16:16,480 --> 00:16:17,440
See you in the next one.