FrequencyOfCharacters

/*
    Given a string, this program prints the characters and their frequencies in alphabetical order
 */

import java.util.Scanner;

public class FrequencyOfCharacters {

    public static void main(String[] args) {

        int max = 26;
        Scanner in = new Scanner(System.in);
        System.out.println("Enter a string to find the frequencies of its characters:");

        // Replaces all the substrings except(^) from characters a-z with the space character and converts them to lower case
        String user_str = in.nextLine().toLowerCase().replaceAll("[^a-z]"," ");

        int[] freq = new int[max];
        char[] string = user_str.toCharArray();

        int i,j;
        for( i=0; i<user_str.length(); i++){
            if(string[i] != ' ') {
                freq[user_str.charAt(i) - 'a']++; // use the ascii code so that a-z have values 0 - 25
            }
        }

        // Print the frequencies of the characters in alphabetical order
        System.out.println("Characters and their corresponding frequencies:");
        for(i = 0; i<max; i++) {
            if( freq[i]!=0) {
                System.out.print((char)(i+'a') + " - " +freq[i] + " ");
                for (j = 0; j < freq[i]; j++) {
                    System.out.print("*");
                }
                System.out.println();
            }
        }
    }
}