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Introduction to 2-D Arrays in java

introducion to 2 d array

Introduction to 2-D Arrays.

Multidimensional Arrays can be defined in simple words as an array of arrays. Data in multidimensional arrays are stored in tabular form (in row-major order).

The 2D array is organized as matrices which can be represented as the collection of rows and columns.

Syntax : 

The syntax of declaring a two-dimensional array is very much similar to that of a one-dimensional array, given as follows.

datatype variable_name[rows][column]

example :

int[ ][ ]  arr = new int[20][20];

How do we access data in a 2D array

The elements of 2D arrays can be randomly accessed. Similar to one-dimensional arrays, we can access the individual cells in a 2D array by using the indices of the cells. There are two indices attached to a particular cell, one is its row number while the other is its column number.

we can store the value stored in any particular cell of a 2D array to some variable a by using the following syntax.

int a = x[i][j]

where x is row index and j is column index 

Initializing 2D Arrays

  •  DIRECT METHOD

data_type[][] variable_name = { {R1C1, R1C2, ….}, {R2C1,R2C2, ….} };

Example: 

int [ ][ ] arr = { { 2 ,  4 } ,  {6, 8 } };

  • USING LOOPS:

We can use loops for initializing 2d array like

for (int i = 0; i < 2; i++)
{
for (int j = 0; j < 2; j++)
{
int a = x[i][j];
}
}

JAVA CODE TO SHOW HOW TO INITIALIZE AND PRINT  2-D ARRAY :

class prepinsta
    public static void main(String[] args
    { 

        int[][][] a = { { { 24 }, { 68 } }; 

        for (int i = 0; i < 2; i++) 
            for (int j = 0; j < 2; j++) 
                    System.out.print(arr[i][j] +” “); 
                    System.out.println();
    } 
output:

2 4

6 8