A 2-D array, or multi-dimensional array, is an array of arrays that represents data in rows and columns. A 2-D array can be declared and initialized in Java by specifying the number of rows and columns, with each element accessed using two indices for the row and column. Elements in a 2-D array must be of the same type, and the array can be initialized either during or after creation by assigning values to each element using its row and column indices.

1. Experts Of
Programming
Created By: Anonymous

2. What is 2-D Array?
• Array of Arrays.
• 2-D array usually represented with rows and columns

3. 2-D Array Declaration
• We can declare 2-D array in following ways
type[][] referencevariable;
or
type referencevariable[][];
For example:
int marks[][];
Each element in the 2-D Array must be the same type.

4. Creation of 2-D Array
arrayreferencevariable = new type[value][value];
For example :
marks = new int[3][4];

5. More on 2-D Array Creation
marks = new int[][] // incorrect;
marks= new int[][4] // incorrect;
marks = new int[3][] // correct;

6. 2-D array in form of rows and columns:
marks=new int[3][4];

7. Initialization of 2-D Array
• After array creation we can initialize the 2-D array like this :
• Arrayvariable[row][column]= value;
• For example lets initialize the marks array :

8. marks[0][0]=8; marks[0][1]=9; marks[0][2]=10; marks[0][3]=7;
8 9 10 7Row 0
Col 0 Col 1 Col 3 Col 4
12 21 30 7
31 45 10 40
Row 1
Row 2
Col 0 Col 1 Col 2 Col 3
Col 0 Col 1 Col 2 Col 3
marks[1][0]=12; marks[1][1]=21; marks[1][2]=30; marks[1][3]=7;
marks[2][0]=31; marks[2][1]=45; marks[2][2]=10; marks[2][3]=40;

9. 8 9 10 7
12 21 30 7
31 45 10 40
Col 0 Col 2 Col 3Col 1
Row 0
Row 1
Row 2
Now if you want to access any element from 2-D array
System.Out.Println(marks[1][2]);
output = 30
System.Out.Println(marks[0][0]);
output = 8

10. We can also initialize the array at the time of
array creation
int[][] marks = new int{
{1,2,0,5},
{4,5,1,4},
{7,6,5,9}
}

11. How we can get array length
marks.length // tell us rows.
marks[0].length // tell us columns.

12. THANKYOU