Let's not look at two dimensional art Gutierrez what we saw in the previous lesson we're one dimensional 2
art is a one dimensional array can be visualized as a sequence of elements laid out along a line in 3
a tree you can visualize elements to be laid out in a great form like in The Matrix. 4
In fact mattresses are usually implemented using tree areas. 5
It's also possible to how arrays of higher dimensions but they are very rare in practice. 6
So let's just go ahead and see how UDRS are created integrated elements are arranged in rows and columns 7
. 8
Here is a two dimensional array that has four rows and columns and has a total of eight elements like 9
a one dimensional array. 10
It is also an object in Java and it can start with primitives an object references index numbering for 11
both rows and columns beginning with zero. 12
Now if this arrays named as my array then my array at indexes 0 and 1 will get it and the element from 13
0 throw unfussy column which has a value of 11. 14
So with this can be implemented using such dreariest. 15
Similarly for the common student example unconsidered would students on their assignments scores in 16
a particular course. 17
Then we can store that information in a query each that can correspond with a student and the values 18
stored in each row can be the assignment of course like in the case of one dimensional arrays. 19
There are three ways to create gutiérrez And they're also created using similar syntax. 20
Let's look at how we can create Overmeyer example. 21
And here's a fast way to do it similar to one dimensional arrays. 22
We use the word new in one dimensional array. 23
We had only one pair of square brackets on either side of the assignment. 24
Since we know how two dimensions we will have two pairs so square brackets on either side of the assignment 25
on the right hand side. 26
The number of rows is indicated in the first square brackets while the number of columns is indicated 27
in the second square brackets. 28
The square brackets on the left hand side will be empty. 29
Let's see how JVM internally implements this to the three Gibeon basically creates a one dimensional 30
array with four elements corresponding to the four rows. 31
And these four elements do not contain the raw data but each of the elements is actually an object reference 32
reference to another and array with two elements. 33
And these are referenced in arrays represent actual rows and they contain the actual data as a byte 34
for the arrays and all of the internal arrays are initialized with default 0. 35
You can also see the two dimensional index numbers associated with each element. 36
So you can see that it is actually implemented as a one be array under elements or simply object references 37
which are done differencing one dimensional address this fact can be observed in the declaration itself 38
. 39
So let's review the declaration once again. 40
We know that an articulation includes a type followed by square brackets which is then followed by the 41
Iranian and we can read it as an army of bike. 42
Now if the pipe is and we can read it as an army off and on we know it is a one dimensional array. 43
Now the pipe itself is trade off and then we can read it as an arc of RF and or in other words on off 44
and of it. 45
So although it doesn't set the machinery in reality it is actually one dimensionality. 46
No not my example elements where any dealings with default value. 47
So we need to initialize them explicitly. 48
And that can be done as shown here. 49
And this is an illustration of how the RL looks after element initialization. 50
Here is the second way to create a query in one be array. 51
We only had commas operator values but we know that a 2D array is an array of some type. 52
So we have one array and within that array we have nested arrays with each an asterisk corresponding 53
to zero and for each history we will have a pair of nested braces on the actual DWB side in that nested 54
braces. 55
Finally as in the case of one dimensional arrays we have this simplest notation. 56
Now here we have something interesting in our Meyera example. 57
We saw that there were four rows on all of the rows were sorting the same number of elements. 58
That is two elements. 59
So each will have two elements but due to the bit Djala implements. 60
Or is it also possible for different rows in a truly array to have different number of elements. 61
So let's see how that's possible. 62
And also where it can be useful. 63
So here we created €2 with duros but we don't specify any value for the number of columns. 64
Next we cleared the first row which would have five elements or five columns Mexicans would be created 65
with two elements. 66
So as you can see the column size is not fixed. 67
Kruskal now has five columns. 68
When the second row has only two columns one example use of this kind of recreation is a symmetric marker 69
X with the number of rows is equal to the number of columns and elements about the diagonal which are 70
shown in red here are simply duplicate of elements below that I acknowledged which are shown in blue 71
. 72
So by creating an array with irregular row sizes begin to watch dooring that duplicate in red. 73
And so the symmetric matrix will now be a triangular matrix as shown here. 74
Each row will be represented by an array of different. 75
In this example frontrow would be an array of length one. 76
Well secondo would be an array of Lendu and so on. 77
So that's a pretty cool way to save some storage space and it would be very useful for very large mattresses 78
like in the case of one dimensional array. 79
Lenth field can also be used on it. 80
However since internally the array is implemented as a one dimensional array accessing lenth from the 81
ARI would return the number of rows in our miring example which are four rows on two columns land would 82
read for accessing left on the first element of my arm would return to this example shows how we can 83
make a reference to one of the rows which is a suburb. 84
So he had a variable called row which is an array is assigned the third row. 85
Since index numbering begins with zero. 86
And that's the end of our discussion on the arrays. 87
Probiotics are sometimes very useful but are much less commonly used than one dimensional allergies 88
later in the first version of our project. 89
We will use two areas similar to the way we extended the syntax from one to two dimensions. 90
We can further extend to higher dimensions dimensions higher than two dimensions are pretty rare in 91
practice