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Array

What Is An Array?

An array is finite ordered set of homogeoneous element.

• Finite :Fixed no of elements
• Ordered :In a sequence or stored in a contiguous block of memory
• Homogeneous : Same type

About Array

• An array is a group of variables of the same data type and referred to by a common name.
• An array consists of a name and the number of elements of the array.
• You can refer to a specific array element by the array name and the element number, which is known as the index number.
• The length of an array is fixed at the time of its creation.
• The following code snippet creates an array named marks: int marks[]=new int[5];

The various types of arrays in Java are:

• One-dimensional arrays
• Multidimensional arrays

1 . One-dimensional arrays

One-dimensional array is a list of variables of the same data type.

Declaration

int marks[]; //Declare array but memory is not allocated yet.

marks=new int[5]; // memory is allocated with new keyword

Or it can be declared in one statement

int marks=new int[5];

Array index always start from zero.

Initialization

x[0]=10;

x[1]=20;

x[2]=5;

x[3]=50;

x[4]=40;

Array can be initialize at the time of declaration

int x[] = new int[5] {10,20,30,40,50} ;

Simplest Way of declaring and initilaizing array

int x[]={10,20,30,40,50};

String name[]={"Ravi","Mohit","Rahul","Rohit","Arun"};

char grade[]={'a','b','c','d','e'};

import java.util.Scanner;
class ArrayTraversing
{
public static vopid main(String...args)
{
int name[]=new int[3];

Scanner ob=new Scanner(System.in);

System.out.println("Insert Values In Array"); 

for(int i=0;i<3;i++)
{
System.out.println("Enter Name"); 
name[i]=ob.next();
}

System.out.println("Value Are"); 

for(int i=0;i<3;i++)
{
System.out.println("Name is"+name[i]); 
}


}

}

2 . Multidimensional arrays

In Java, multidimensional arrays are actually arrays of arrays.To declare multidimensional arrays, you need to specify multiple square brackets after the array name.

The following code snippet creates a two-dimensional array:

int multiDim[] = new int[3][];

In a multidimensional array, you need to allocate memory for only the first dimension, as shown in the following code snippet:

multiDim[0] = new int[4];

multiDim[1] = new int[4];

multiDim[2] = new int[4];

In addition, when you allocate memory to the second dimension of a multidimensional array, you need not allocate the same number to each dimension.

Declare Twodimensional Array

int x[3][3]=new int[3][3] ;

Initialize Twodimensional Array

x[0][0]=10;

x[0][1]=20;

x[1][0]=5;

x[1][1]=50;

x[2][0]=40;

x[2][1]=40;

class TraverseTwoDArray
{  
public static void main(String... args)
{  

//declaring and initializing 2D array  
int val[][]={{3,4,5},{2,2,5},{1,2,3}};  
  
//Display 2D array  
for(int i=0;i<3;i++)
{  
 for(int j=0;j<3;j++)
   {  
   System.out.print(val[i][j]+" ");  
   }  
 System.out.println();  
}  
  
}
} 

import java.util.Scanner.*;
class TraverseTwoDArray2
{  
public static void main(String... args)
{  

//declaring and initializing 2D array  
int val[][]=new int[3][3];  

//Create Scanner Object  
Scanner ob=new Scanner(System.in);

//Get User Input  
for(int i=0;i<3;i++)
{  
 for(int j=0;j<3;j++)
   {  
    System.out.println("Enter Value for "+i+" "+j);
    val[i][j]=ob.nextInt();  
   }  

}  

//Display 2D array  
for(int i=0;i<3;i++)
{  
 for(int j=0;j<3;j++)
   {  
   System.out.print(val[i][j]+" ");  
   }  
 System.out.println();  
}  
  
}
}