Arrays of Arrays

Since arrays themselves are objects, we can have arrays of arrays.

When we first started making arrays, we added a single [] to a variable name to tell Java it was an array.

int[] arr = new int[5]; // array of 5 ints

To make arrays of arrays, we add another [].

int[][] arr2d = new int[5][5]; // array of 5 arrays of 5 ints

We call these arrays of arrays multidimensional arrays.

• A multidimensional array with two []s would be called a two-dimensional array.

Practice Exercise

The total number of square brackets in the declaration determines the number of dimensions for each array.

// Each of these declares a two-dimensional array of ints:
int[][] a2d1;
int[]   a2d2[];
int     a2d3[][];

// Not great style, but legal:
int[] oned, twod[], threed[][];

---

Prev -- Up -- Next