Array in Java

Array is a collection similar data type.  Java provides a data structure, the array, which stores a fixed-size sequential collection of elements of the same type. An array is used to store a collection of data, but it is often more useful to think of an array as a collection of variables of the same type.

        

Creating Arrays:

dataType[] arrayRefVar;

arrayRefVar = new dataType[arraySize];

or

dataType[] arrayRefVar = {value0, value1, ..., valuen};

Example -:   double[ ] myList = new double[10];

Types of Array in java

There are two types of array.

·         Single Dimensional Array

·         Multidimensional Array

Example of Single Dimensional 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.print(a[i]+ " "); 

 

}

 

     

Output-:  10   20    70     40     50

 

Multidimensional array in java

Declare of multidimensional array -: dataType[][] arrayRefVar; (or) 

dataType [][]arrayRefVar; (or) 

dataType arrayRefVar[][]; (or) 

dataType []arrayRefVar[];

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

Initialized multidimensional array

arr[0][0]=1; 

arr[0][1]=2; 

arr[0][2]=3; 

arr[1][0]=4; 

arr[1][1]=5; 

arr[1][2]=6; 

arr[2][0]=7; 

arr[2][1]=8; 

arr[2][2]=9;

Example of multidimensional array

class Sample{ 

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(); 

} 

 

}

}

 

Example of array with using for loop

public class Sample {

 

   public static void main(String[] args) {

      double[] myList = {1.9, 2.9, 3.4, 3.5};

 

      // Print all the array elements

      for (double element: myList) {

         System.out.println(element);

      }

   }

}

Output-:

1.9

2.9

3.4

3.5

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.

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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