ARRAYS - Java Programming: From Problem Analysis to Program Design - page 591

The preceding two statements can be combined into one statement, as follows:

dataType[][] arrayName = new dataType[intExp1][intExp2];

For example, the statement:
double [][] sales = new double [10][5];
declares a two-dimensional array sales of 10 rows and 5 columns, wherein every element is
of type double initialized to the default value of 0.0 . As in a one-dimensional array, the
rows are numbered 0...9 and the columns are numbered 0...4 (see Figure 9-16).

sales

[0] [1] [2] [3] [4]

[0] 0.0 0.0 0.0 0.0

0.0 0.0 0.0 0.0 0.0
0.0 0.0 0.0 0.0 0.0
0.0 0.0 0.0 0.0 0.0
0.0 0.0 0.0 0.0 0.0

0.0

[1]

[2]

[3]

[4]

[5]
[6]

0.0 0.0 0.0 0.0 0.0

0.0 0.0 0.0 0.0 0.0

[7] 0.0 0.0 0.0 0.0 0.0

[8]

0.0 0.0 0.0 0.0 0.0

[9] 0.0 0.0 0.0 0.0 0.0

9

Two-dimensional array sales FIGURE 9-16

From this point forward, whenever we instantiate a two-dimensional array and draw its
diagram, all the default values may not be shown as they are in Figure 9-16.

Accessing Array Elements
To access the elements of a two-dimensional array, you need a pair of indices: one for the
row position, and one for the column position.
The syntax to access an element of a two-dimensional array is:

arrayName[indexExp1][indexExp2]

where indexExp1 and indexExp2 are expressions yielding nonnegative integer values.
indexExp1 specifies the row position and indexExp2 specifies the column position. More-
over, the value of indexExp1 must be nonnegative and less than the number of rows, and the
value of indexExp2 must be nonnegative and less than the number of columns in the array.