Java program to check frequency of characters in a string

June 2, 2020

Check frequency of character in a string

Finding the frequency of a character in a string, means we have to check how many times a particular character is present in that string. Here, we have coded a Java Program for the same. Let’s take an example of a string “prepinsta” . In which we have to check that how many times each of the characters gets repeated in the string.

Algorithm

Take string input from user and store it in the variable called “str”.
After that make freq array having size of length of string.
Convert string to char array .
Run for loop start from i=0 to str<length() store 1 to freq array.
Run j loop start from i=i+1 to j<str.length().
check condition if(string[i] == string[j]) then do freq[i]++ and set string[j]=’0′ .
After that display frequency of character one by one.

Code in Java

import java.util.Scanner;

public class FrequencyOfCharactersInAString {
   public static void main(String[] args) {
    Scanner sc =new Scanner(System.in);
     System.out.print("Enter String : ");
     String str = sc.nextLine(); 
     int[] freq = new int[str.length()]; 
     int i, j; 

     //Converts given string into character array 
     char string[] = str.toCharArray(); 
     for(i = 0; i <str.length(); i++) { 
        freq[i] = 1; 
          for(j = i+1; j <str.length(); j++) { 
            if(string[i] == string[j]) { 
            freq[i]++; 

           //Set string[j] to 0 to avoid printing visited character 
            string[j] = '0'; 
          } 
       } 
    } 
    //Displays the each character and their corresponding frequency 
    System.out.println("Characters and their corresponding frequencies"); 
    for(i = 0; i <freq.length; i++) { 
       if(string[i] != ' ' && string[i] != '0') 
          System.out.println(string[i] + "-" + freq[i]); 
       } 
   }
}
This code is contributed by Shubham Nigam (Prepinsta Placement Cell Student)

Output

Enter String : prepinsta
Characters and their corresponding frequencies
p-2
r-1
e-1
i-1
n-1
s-1
t-1
a-1