Multidimensional arrays in Java

DrRakha

Multidimensional arrays
If you are a java developer so it is for sure you are dealing with arrays, in java you can create 1, 2 or 3 dimensional arrays, in this article we go throw how to use multidimensional arrays in java. For memory allocations, java uses an approach named “Arrays of Arrays” where java establishes a multidimensional array from a group of one dimensional arrays and not like other approaches that reserve a blocks in memory.

1-dimensional arrays:
For one 1dimensional array you will have only one row and you will have to specify its length in allocation step. You first will declare a 1D array as follows:

Code:

int[] array1D; // Declares 1D array.

And you do memory allocation as follows:

Code:

array1D = new int[5]; // memory allocation

You do these two steps in only one:

Code:

int array1D = new int[5];

This creates a one array of 5 elements. Note that the index start from zero, following snippet fills a 1D array and prints its content:

Code:

  array1D[0]=54;
            array1D[1]=11;
            array1D[2]=43;
            array1D[3]=74;
            array1D[4]=84;


            for(int i=0;i<array1D.length;i++)
            {
                System.out.println("Element#"+(i+1)+" - "+array1D[i]);
            } 

The output is as follows:

Code:

Element#1 - 54
Element#2 - 11
Element#3 - 43
Element#4 - 74
Element#5 - 84

2-dimensional arrays
For creating 2D dimensional arrays you will need to define the number of rows and columns in your array, the declaration and allocation is as follows:

Code:

int[][] array2D = new int[3][6];

The previous line creates a 2d dimensional array; this actually creates 7 objects, one dimensional array of 6 elements for each for the rows, and a one dimensional array of 3 elements. Following snippet adds data and prints it to a 2D array:

Code:

    int[][] array2D=  new int[3][6];
            array2D[0][4]=54;
            array2D[1][5]=11;
            array2D[2][2]=43;
           

            System.out.println("array2D.length: "+array2D.length);
            System.out.println("array2D[0].length: "+array2D[0].length);
            for(int i=0;i<array2D.length;i++)
                for(int j=0;j<array2D[0].length;j++)
            {
                System.out.println("Element#"+(i+1)+","+(j+1)+" - "+array2D[i][j]);
            }
 

The output of this snippet is as follows:

Code:

array2D.length: 3
array2D[0].length: 6
Element#1,1 - 0
Element#1,2 - 0
Element#1,3 - 0
Element#1,4 - 0
Element#1,5 - 54
Element#1,6 - 0
Element#2,1 - 0
Element#2,2 - 0
Element#2,3 - 0
Element#2,4 - 0
Element#2,5 - 0
Element#2,6 - 11
Element#3,1 - 0
Element#3,2 - 0
Element#3,3 - 43
Element#3,4 - 0
Element#3,5 - 0
Element#3,6 - 0
 

3-dimensional arrays
It works same as 2d dimensional array as you can do allocation as follows:

Code:

int[][][] array3D= new int[3][6][7];

DrRakha

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Multidimensional arrays in Java

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