JAVA ARRAY

JAVA ARRAY

—Arrays are objects that store multiple variables of the same type.

— However, an array itself is an object on the heap.

—Array in Java is index-based, the first element of the array is stored at the 0th index, 2nd element is stored on 1st index and so on.

—DECLARING ARRAY

Data type [ ] arrayname;

•INSTANTIATING AN ARRAY IN JAVA

—var-name = new type [size];

—Example:

—int intArray[]; //declaring array intArray = new int[20]; // allocating memory to array

Single dimentional array

Example 1

class Testarray

{  

public static void main(String args[]){  

int a[]=new int[5];//declaration and instantiation  

a[0]=10;//initialization  

a[1]=20;  

a[2]=70;  

a[3]=40;  

a[4]=50;  

for(int i=0;i<a.length;i++)//length is the property of array  

System.out.println(a[i]);  

}

}  

—  Example 2

class Testarray1

{  

public static void main(String args[])

{  

  int a[]={33,3,4,5};//declaration, instantiation and initialization    

  for(int i=0;i<a.length;i++)//length is the property of array  

  System.out.println(a[i]);  

}

}  

MULTIDIMENSIONAL ARRAY IN JAVA

—In such case, data is stored in row and column based index (also known as matrix form).

Syntax

—dataType[][] arrayRefVar;

Example

int[][] arr=new int[3][3];//3 row and 3 column  

—

class Testarray3

{  

public static void main(String args[])

{  

  int arr[][]={{1,2,3},{2,4,5},{4,4,5}};    

  for(int i=0;i<3;i++)

  {  

   for(int j=0;j<3;j++)

  {  

     System.out.print(arr[i][j]+" ");  

  }  

   System.out.println();  

  }  

}

}  

—