Multidimensional Arrays
A multidimensional array is an array of arrays.
Multidimensional arrays are useful when you want to store data as a tabular form, like a table with rows and columns.
To create a two-dimensional array, add each array within its own set of curly braces:
Example
int[][] myNumbers = { {1, 2, 3, 4}, {5, 6, 7} };
myNumbers is now an array with two arrays as its elements.
Access Elements
To access the elements of the myNumbers array, specify two indexes: one for the array, and one for the element inside that array. This example accesses the third element (2) in the second array (1) of myNumbers:
Example
int[][] myNumbers = { {1, 2, 3, 4}, {5, 6, 7} };
System.out.println(myNumbers[1][2]); // Outputs 7
Remember that: Array indexes start with 0: [0] is the first element. [1] is the second element, etc.
Change Element Values
You can also change the value of an element:
Example
int[][] myNumbers = { {1, 2, 3, 4}, {5, 6, 7} };
myNumbers[1][2] = 9;
System.out.println(myNumbers[1][2]); // Outputs 9 instead of 7
Loop Through a Multi-Dimensional Array
You can also use a for loop inside another for loop to get the elements of a two-dimensional array (we still have to point to the two indexes):
Example
int[][] myNumbers = { {1, 2, 3, 4}, {5, 6, 7} };
for (int i = 0; i < myNumbers.length; ++i) {
for (int j = 0; j < myNumbers[i].length; ++j) {
System.out.println(myNumbers[i][j]);
}
}
Or you could just use a for-each loop, which is considered easier to read and write:
Example
int[][] myNumbers = { {1, 2, 3, 4}, {5, 6, 7} };
for (int[] row : myNumbers) {
for (int i : row) {
System.out.println(i);
} }