Array in Java

Array is like a Basket. We carried basket when we are going to market. In a basket we can store apple, banana, vegetables etc. Here array is same like basket.

In array we can store homogeneous (Similar type) type of data. An array is an indexed collection of homogeneous data element (value). Every value is store in array based on indexed. In array we can store multiple values.

Advantage of Array

Disadvantage of Array

Types of Arrays

4 types of array are in Java language.

1D or Single Dimensional Array

In single dimensional array we can store only single data type value. Single variable but one " [ ] " subscript.

We can't initialize the size of array at the time of declaration.

In two ways we can initialize the 1D array

1. Compile time initialization

Further in compile time initialization we have two types initialization.

Single line initialization

Syntax:


    int a[] = {5,4,3};
    int []a = {5,4,3};
    int a[3] = {5,4,3}; //invalid declaration

Multiline initialization

Syntax:

    
    int a[] = new int[3];
    a[0] = {2};
    a[1] = {6};
    a[2] = {3};

2. Runtime initialization

We initialize the value of array at runtime.

Program of 1D array runtime initialization:


    import java.util.*;
	class Test7
	{
		public static void main(String arg[])
		{
			Scanner sc = new Scanner(System.in);
			int a[] = new int[5];
			int i;
			for(i=0; i<a.length; i++)
			{
				System.out.print("Elements a["+i+"] : ");
				a[i] = sc.nextInt();
			}
		}
	}

Output:


	Enter the Size of Array
	Elements a[0] : 5
	Elements a[1] : 6
	Elements a[2] : 5
	Elements a[3] : 3
	Elements a[4] : 1

2D Array

In 2D or multi-dimensional array we can store multiple data value with single variable in the form of row and column with two ( [row][column] ) subscript. Array brackets are called subscript.

In java 2D array implemented as an array of array.

Advantage of 2D array

In two ways we can initialize the 2D array

1. Compile time initialization

Further in compile time initialization we have two types initialization.

Single line initialization

Syntax:


    int a[][] = {{1,2},{3,4},{5,6}};
    int [][]a = {{1,2},{3,4},{5,6}};
    int a[3][] = {{1,2},{3,4},{5,6}}; //invalid declaration

Multiline initialization

Syntax:

    
    int a[][] = new int[3][2];
    a[0][0] = 1;
    a[0][1] = 2;
    a[1][0] = 3;
    a[1][1] = 4;
    a[2][0] = 5;
    a[2][1] = 6;

2. Runtime initialization

We initialize the value of array at runtime.

Program of 2D array runtime initialization:


	import java.util.*;
	class Test8
	{
		public static void main(String arg[])
		{
			System.out.println("Enter the Size of Array");
			Scanner sc = new Scanner(System.in);
			int a[][] = new int[3][3];
			int i, j;
			for(i=0; i<a.length; i++)
			{
				for(j=0; j<3; j++)
				{
			System.out.print("Enter elements a["+i+"]["+j+"] : ");
				a[i][j] = sc.nextInt();
				}
			}
			for(i=0; i<a.length; i++)
			{
				for(j=0; j<3; j++)
				{
				System.out.print(a[i][j]+" ");
				}
				System.out.println();
			}
		}
	}

Output:


	Enter elements a[0][0] : 1
	Enter elements a[0][1] : 2
	Enter elements a[0][2] : 3
	Enter elements a[1][0] : 4
	Enter elements a[1][1] : 5
	Enter elements a[1][2] : 6
	Enter elements a[2][0] : 7
	Enter elements a[2][1] : 8
	Enter elements a[2][2] : 9
	
	1 2 3
	4 5 6
	7 8 9

3D or multi dimensional

In 3D or multi dimensional array we can store multiple data value with single variable in the form of row and column with three ( [ ][ ][ ] ) subscript. Array brackets are called subscript.

Very rare case people use 3D array. Mostly we use 1D or 2D array in Java. In java 3D array implemented as an array of array

In two ways we can initialize the 3D array or multi dimensional

1. Compile time initialization

Further in compile time initialization we have two types initialization.

Single line initialization

Syntax:

	
	int a[][][] = {{1,2},{5,6},{7,8}};

Multiline initialization

Syntax:


	int a[][][] = new int[3][2][2];
	a[0][0][0] : 1
	a[0][0][1] : 2
	a[0][1][0] : 3
	a[0][1][1] : 4
    
	a[1][0][0] : 1
	a[1][0][1] : 2
	a[1][1][0] : 3
	a[1][1][1] : 4
    
	a[2][0][0] : 1
	a[2][0][1] : 2
	a[2][1][0] : 3
	a[2][1][1] : 4

2. Runtime Initialization

We initialize the value of array at runtime.

Program of 3D array runtime initialization:


	import java.util.*;
	class Test9
	{
	public static void main(String arg[])
    	{
     	Scanner sc = new Scanner(System.in);
     	int a[][][] = new int[3][2][2];
      	int i, j, k;
    
      	for(i=0; i<a.length; i++)
      	{
        	for(j=0; j<2; j++)
         	{
           	for(k=0; k<2; k++)
           	{
            	System.out.print("Enter elements a["+i+"]["+j+"]["+k+"] : ");
	   	a[i][j][k] = sc.nextInt();
            }
          }
       }
	
    	System.out.println("Displaying Result in Matrix form: ");
     	for(i=0; i<a.length; i++)
      	{
        	for(j=0; j<2; j++)
         	{
           	for(k=0; k<2; k++)
           	{
            	System.out.print(a[i][j][k]+" ");	  
            }
        }
        System.out.println();
       }
     }
}

Output


	Displaying Result in Matrix form:
	1 2 3 4
	5 6 7 8
	9 10 11 12

Anonymous Array

Some time we create an array in java without name such type nameless array called anonymous array.

Why we create anonymous array in java?

Syntax of anonymous array:


	new data-type[] {elements};

Example of anonymous array:


	//pending

Output


	//pending
PREVIOUS
NEXT

Post Your Comment

↑