Java program to find frequency count for an array item

Problem Statement

Given an unsorted array of n integers. Elements can be repeated multiple times in the array. Write a java program to find frequency count of an array item.

 

Java Program

public class ArrayFrequency {

    public static void main(String[] args) {
        int n;
        Scanner input = null;
        int[] a = null;
        try {
            input=new Scanner(System.in);
            System.out.println("Enter size of the array:");
            n= input.nextInt();

            if(n > 0) {
                a=new int[n];
                System.out.println("Enter array elements:");
                for (int i = 0; i < n; i++) {
                    a[i] = input.nextInt();
                }
            }else{
                System.out.println("Enter positive number.");
                System.exit(0);
            }

            System.out.println("Input Array:");
            printArray(a);

            System.out.println("Enter the array element to 
find frequency:");
            int item= input.nextInt();

            int count = frequencyCount(a,item);

            if(count == 0 ) {
                System.out.println("Item NOT FOUND in the array");
                System.exit(0);
            }
            else{
                System.out.println("Frequency count of item:" + count );
            }

        }catch (InputMismatchException ime) {
            System.out.println("Not a valid input");
        }
        catch (Exception e) {
            e.printStackTrace();
        } finally {
            if(input!=null)
            {input.close();}
        }
    }

    private static void printArray(int[] a){
        for (int anA : a) {
            System.out.print("[ " + anA + " ]");
        }
        System.out.println( "");
    }

    private static int frequencyCount(int[] a, int value) {
        int frequency = 0;
        for (int i=0; i<a.length; i++)
            if (a[i] == value)
                ++frequency;
        return frequency;
    }
}

 

Run output of the program:

TestCase 1

Enter size of the array:
6
Enter array elements:
45
33
68
45
27
104
Input Array:
[ 45 ][ 33 ][ 68 ][ 45 ][ 27 ][ 104 ]
Enter the array element to find frequency:
45
Frequency count of item:2

TestCase 2

Enter size of the array:
6
Enter array elements:
45
33
68
45
27
104
Input Array:
[ 45 ][ 33 ][ 68 ][ 45 ][ 27 ][ 104 ]
Enter the array element to find frequency:
99
Item NOT FOUND in the array

 

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