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We can use two dimensional arrays to store data that come in the form of a table.

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Let's imagine you have a list of grades for one student, Harry, Harry, go to 70 to a 74, a 78 and

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a 76 in his courses.

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Now an array of integers can easily store this list of data, but what if there are more students?

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This data isn't a list anymore.

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It's a table with three rows.

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So it looks like we're going to need three arrays to store each row of data.

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OK, sure, that's fine, but what if there are one students?

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Are you going to create a hundred a raise?

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I sure hope not.

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Because when your data comes in the form of a table or a grid, you need to use it to the array, which

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would look something like this.

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And it's a lot easier to manage one array as opposed to hundreds.

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So in this lesson, you're going to learn when to work with two drays.

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First things first, create a new file name to erase Java, to erase an inside the class, make the

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main method.

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So what is it to Deira, a tutera is an array that contains a race.

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Two degrees are perfect when your data is in the form of a grid or a table.

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Every row in this table is like its own array.

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One array can store the first row of data, a second array can store the second row of data, and a

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third array can store the third row of data.

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But instead of creating many integer arrays to store individual rows, we can bundle this data into

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a two Deira.

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The studio array is capable of storing every row in this table.

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Because this Todora has three rows and each row is like its own array, and we can access each row with

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an index that goes from zero to two.

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Also each row, each array contains elements with indexes that go from zero to three.

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And so in order to create a tutera, you need to write the type of data you're storing with two brackets.

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This means we're creating a two tier array of integer values.

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The first bracket is the number of rows.

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So we're basically creating a table with three rows.

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And the second bracket is the number of elements in each row.

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In this case, each row of data is going to contain four elements.

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And so from a visual standpoint, this code is going to create an array with three rows and four columns

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and by default every value is going to start at zero.

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Let's try it out inside your glass, create an array with three rows and four columns into grades is

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equal to a new integer to Deira.

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The first bracket is the number of rows we're going to have three rows, the second bracket is the number

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of elements in each row and each row is going to have four elements.

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OK, what now?

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So we have three rows and each row is basically an array with four elements, we can grab the row or

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in other words, the array of values at index zero, one or two.

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Now, in our code, we can index each array and print its contents using arrays not to string.

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You can print there, right, index zero.

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The IRAD Index one and the red index to.

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And as expected, each row is an array with four elements, the first array has Harrys grades, the

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second one run and the third one her minie.

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So I'm going to print some messages to reflect this.

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I'll put a tab of space.

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Followed by Harry and a Colin.

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I'll do the same thing for the next two print statements.

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And her mighty.

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All right, we're off to a pretty good start.

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So how do you update to Dré values, just like before you can update Arae values from their index?

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You can access any item in this table with two indexes, if I want to change your mind is great and

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charm's the first index is the area we're interested in.

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In this case, Hurum fetching the ROE and fetching the array with an index of two.

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The second index refers to the element in that array.

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In this case, I'm grabbing the value that's inside row two and has an index of three within that row.

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So at this information, I can start by updating Harry's grades.

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All of Harry's grades are in the first row, row zero, so the first bracket is going to index the array,

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the road that we're interested in.

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And we can use the second bracket to index a specific element in zero, Harry got a seventy two in potion.

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A 74 in herbology.

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A 78 and Earthman, see?

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And a seventy six and charm's.

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I can go ahead and run the code.

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And as you can see, this updates every element in the first story.

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Now we're going to do the same thing for a run in her money runs.

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Grades are in the second row, the row with an index of one.

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So once again, we use the first bracket theory we're interested in and then we can use the second bracket

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to index a specific element in a row one.

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Ron got a 65 and potion.

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A 64 in herbology.

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A 61 in Earthman, see?

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And a 67 and charm's.

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And we can replicate this logic for her Chinese grades.

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I can run my code.

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And everything works out.

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Hope you can appreciate that two ideas are perfect when you want to store a table of data instead of

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using multiple one dimensional arrays to store each row individually.

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We can use that to Deira to store the entire table at once.

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I want to introduce a faster way of initializing to dress, because the code is getting a bit long since

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we already know what the values are, we can create the array and define the values in one line.

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This code is going to create a two tier with three rows of values.

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Each row is an array bundled in a 2D array.

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So we'll try this out in our code.

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Each arrow of data is basically an array, so we need one array to store Harry's grades.

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One array to store runs grades.

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And another to store her mind is.

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Runner code.

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And everything works as it should, the code looks a lot better.

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OK, so how do we access each value in a tutera?

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Once again, we can access each value using the two indexes.

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If I want to access her mind is great and Charm's the first inducts gets the array, it gets the row

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with all of her grades and the second index gets the grade that we're interested in.

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So I'm going to wrap up this lesson by printing all of their grades as part of a string.

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Once again, we used the first bracket to specify the road that we were interested in, all of Harry's

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grades are in the first row zero and his potions grade can be found in index zero of the first row.

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His herbology grade is an index one.

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Earthman index to.

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And Charm's Index three.

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I can do the same thing with Iran, except that all of his grades are in the second row, row one.

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And we can wrap up by doing the same thing with her mind greats.

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They're all in the third row row to.

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And that's perfect, you created an array that stores three rows of data and then you accessed every

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value in this table using the indexes.

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We always start with the index of the array, followed by an index for the item inside.

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In this lesson you learn to work with, to raise a Deira is an array that contains a race, each row

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of values is an array bundled in a tiara.

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This makes them perfect for storing a table of data.

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That's because each array is like a row inside of a table and you can access any value in the table

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using the index as the first index fetches the array that we're interested in and the second index gets

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the element inside the array.