How to grab only a certain row of a two-dimensional matrix in java?

Question

When I have a two-dimensional matrix in java, but I only want to work with a certain row of that matrix respectively creating a new array that contains the contents of the matrix in that certain row, how would I accomplish that (with primitives)?

So, for example, we would write:

int[][] matrix = new int[10][10];

Now we have a two-dimensional matrix with 10 rows and 10 columns. Assume that we fill the whole matrix with certain elements, and now, I wish to work only with the first row, meaning to define a new array that contains exactly the elements of the first row of the matrix.

Answer 1

Assuming that row means the horizontal segments of the matrix (as it almost always is):

In a 2 dimensional array in java, the rows are the first index and the columns are the second index.
Basically a two dimensional array is an array of arrays. So

int[][] intArray = new int[10][3];

is actually an array of size 10. Each element in the array is an array in itself of size 3.

Say you have an array of integers

int[][] integerArray; //we have to initialize the array.

then we want to work with the 1st row. We would use:

int[] arr = integerArray[0];

LIMITATIONS

1. The matrix must be initialized (must have values in cells)
2. The matrix must have a 1st row

Note: we use integerArray[0] because arrays start at index 0, so the third row would be integerArray[2]