Array in Java

→ Array is a collection of similar type of elements that have contiguous memory location.

→ It is an object the contains elements of similar data type.

→ Its index start from 0.

Advantages

Code optimization: We can retrieve or sort the data easily.
Random Access: We can get any data located at any index position.
Type safe

Disadvantages

Size Limit: We can store only fixed size of elements in the array. It doesn't grow its size at runtime.

Types of Array in java

There are 2 types of array.

Single Dimensional Array
Multidimensional Array

Single Dimensional Array in java

Syntax

dataType[] arr; (or)
dataType []arr; (or)
dataType arr[];

Single Dimensional Java Array

Where we are going to declare, instantiate, initialize and traverse an array.

class Single{  
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++)   
System.out.println(a[i]);  
}}  

Declaration, Instantiation and Initialization in array

Example

class Testarray1{  
public static void main(String args[]){  
int a[]={30,35,40,50};//declaration, instantiation and initialization  
for(int i=0;i<a.length;i++)   
System.out.println(a[i]);  
}}  

Multidimensional array in java

Data is stored in row and column based index (also known as matrix form).

Syntax

dataType[][] arrayRefVar; (or)  
dataType [][]arrayRefVar; (or)  
dataType arrayRefVar[][]; (or)  
dataType []arrayRefVar[];

Example

class Dimensional{  
public static void main(String args[]){  
//creating two matrices  
int a[][]={{1,3,4},{3,4,5}};  
int b[][]={{1,3,4},{3,4,5}};  
//creating another matrix to store the sum of two matrices  
int c[][]=new int[2][3];  
//adding and printing addition of 2 matrices  
for(int i=0;i<2;i++){  
for(int j=0;j<3;j++){  
c[i][j]=a[i][j]+b[i][j];  
System.out.print(c[i][j]+" ");  
}  
System.out.println();//new line  
}  
}}  

Output

       2 6 8
       6 8 10

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OOPs Concepts

Array in Java

Advantages

Disadvantages

Types of Array in java

Single Dimensional Array in java

Syntax

Single Dimensional Java Array

Declaration, Instantiation and Initialization in array

Example

Multidimensional array in java

Syntax

Example