Java Array

Normally, array is a collection of similar type of elements that have contiguous memory location.

Java array is an object the contains elements of similar data type. It is a data structure where we store similar elements. We can store only fixed set of elements in a java array.

Array in java is index based, first element of the array is stored at 0 index.

Advantage of Java Array

• Code Optimization: It makes the code optimized, we can retrieve or sort the data easily.
• Random access: We can get any data located at any index position.

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Disadvantage of Java Array

• Size Limit: We can store only fixed size of elements in the array. It doesn't grow its size at runtime. To solve this problem, collection framework is used in java.

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Types of Array in java

There are two types of array.

• Single Dimensional Array
• Multidimensional Array

Syntax to Declare an Array in java

dataType[] arr; (or)  

dataType []arr; (or)  

dataType arr[]; 

Instantiation of an Array in java

arrayRefVar=new datatype[size]; 

Example of single dimensional java array

    

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;  

  

//printing array  

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

System.out.println(a[i]);  

  

}}   

Syntax to Declare Multidimensional Array in java

dataType[][] arrayRefVar; (or)  

dataType [][]arrayRefVar; (or)  

dataType arrayRefVar[][]; (or)  

dataType []arrayRefVar[];   

Example to instantiate Multidimensional Array in java

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

Example of Multidimensional java array

class Testarray3{  

public static void main(String args[]){  

  

//declaring and initializing 2D array  

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

  

//printing 2D array  

for(int i=0;i<3;i++){  

 for(int j=0;j<3;j++){  

   System.out.print(arr[i][j]+" ");  

 }  

 System.out.println();  

}  

  

}}