Java Reference
In-Depth Information
Similarly, suppose that we want to process column number
2
(the third column) of
matrix
. The elements of this column are:
matrix[0][2], matrix[1][2], matrix[2][2], matrix[3][2], matrix[4][2],
matrix[5][2], matrix[6][2]
Here, the second index (the column position) is fixed at
2
. The first index (the row
position) ranges from
0
to
6
. In this case, we use the following
for
loop to process
column
2
of
matrix
:
for
(
int
row = 0; row < matrix.length; row++)
//process matrix[row][2]
This
for
loop is equivalent to the following
for
loop:
int
col = 2;
for
(
int
row = 0; row < matrix.length; row++)
//process matrix[row][col]
Next, we discuss some specific algorithms for processing two-dimensional arrays.
INITIALIZATION
Suppose that you want to initialize the elements of row number
4
(the fifth row) to
10
. As explained earlier, the following
for
loop initializes the elements of row number
4
to
10
:
int
row = 4;
for
(
int
col = 0; col < matrix[row].length; col++)
matrix[row][col] = 10;
9
If you want to initialize the elements of the entire
matrix
to
10
, you can also put the first
index (the row position) in a loop. By using the following nested
for
loops, you can
initialize each element of
matrix
to
10
:
for
(
int
row = 0; row < matrix.length; row++)
for
(
int
col = 0; col < matrix[row].length; col++)
matrix[row][col] = 10;
PRINT
By using a nested
for
loop, you can output the elements of
matrix
. The following
nested
for
loops print the elements of
matrix
, one row per line:
for
(
int
row = 0; row < matrix.length; row++)
{
for
(
int
col = 0; col < matrix[row].length; col++)
System.out.printf("%7d", matrix[row][col]);
System.out.println();
}
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