Java Multi-Dimensional Arrays

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:

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:

int[][] myNumbers = { {1, 2, 3, 4}, {5, 6, 7} };
System.out.println(myNumbers[1][2]); // Outputs 7

Change Element Values

You can also change the value of an element:

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):

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:

int[][] myNumbers = { {1, 2, 3, 4}, {5, 6, 7} };
for (int[] row : myNumbers) {
  for (int i : row) {
    System.out.println(i);
  }
}