2D Arrays in Java

In Java, a table may be implemented as a 2D array. Each cell of the array is a variable that can hold a value and works like any variable. As with one dimensional arrays, every cell in a 2D array is of the same type. The type can be a primitive type or an object reference type.

Important: Each cell of the array is specified with a row and column number, in that order.

Say that gradeTable is a 2D array of int, and that (conceptually) it looks like the table to the right. Then,

gradeTable[ 0 ][ 1 ]     // holds 42
gradeTable[ 3 ][ 4 ]     // holds 93
gradeTable[ 6 ][ 2 ]     // holds 78

The subscripted variables are used in assignment statements and arithmetic expressions just like any variable:

// puts a 33 into row 0 column 1. 
gradeTable[ 0 ][ 1 ] = 33 ;  

// increments the value at row 3 column 4.
gradeTable[ 3 ][ 4 ]++ ;

// puts 40 into value 
int value = (gradeTable[ 6 ][ 2 ] + 2) / 2 ;