Write a java program to Count Sequential Characters.

Write Java code to count the number of characters that get repeated 3 times consecutively and return that count (ignore case). Get a string as input. If no character gets repeated 3 times consecutively return -1. The return type of the output is the repeat count.

Input and Output Format

• Input consists of a string.
• The output is an integer.

Refer sample output for formatting specifications

Sample Input 1:

abcXXXabc

Sample Output 1:

1

Sample Input 2:

aaaxxyzAAAx

Sample Output 2:

2

Count Sequential Characters in Java

Following are the steps to count sequential characters in Java:

• Input a string.
• Call the consecutiveRepeatingOfChar() method with the input string.
• Inside the method, declare and initialize variables c and n with 0.
• Iterate over the string, and check for the following condition
  • If the character at ith position is equal to the i+1 position then increment n value.
  • Otherwise, set n to 0.
  • Next, if the value of n is 2 then increment the value of count in the c variable.
• At last, return value of count i.e c variable.

import java.util.Scanner;

public class Main {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    String input1 = sc.nextLine();
    System.out.println(consecutiveRepeatitionOfChar(input1));
  }

  public static int consecutiveRepeatitionOfChar(String input1) {
    int c = 0;
    int n = 0;
    for (int i = 0; i < input1.length() - 1; i++) {
      if (input1.charAt(i) == input1.charAt(i + 1))
        n++;
      else
        n = 0;
      if (n == 2)
        c++;
    }
    return c;
  }
}

Output

Count Frequency of characters in Java

Write a program in Java to count the number of frequency of characters in the string. Let ‘aaabbbcc’ be a string and the count of characters will be ‘a3b3c2’.

Input and Output Format

• Input consists of a string.
• The output of a string with an integer value.

Refer sample output for formatting specifications

Sample Input 1:

aaaXXXcc

Sample Output 1:

a3 X3 c2

Program to count frequency of characters in Java

Following is the step we will follow to count the count frequency of characters:

• Input a string from the user.
• Iterate over the string and for each iteration increment count value.
• Repeat this process till the character at i^th position matches the next character.
• At last print that character with its count.

package com.company;

import java.util.Scanner;

public class Practice11 {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        String str = scanner.next();
        int count;
        for(int i = 0;i<str.length();i++){
          count = 1;
            while(i+1<str.length() && str.charAt(i)==str.charAt(i+1)){
                i++;
                count++;
            }
            System.out.print(str.charAt(i)+""+count+" ");
        }
    }

}

Output

Count of Occurrence of each character using HashMap

Write a program in Java to count the number of occurrences of characters in the string using HashMap. Let ‘aaabbbcc’ be a string and the count of characters will be ‘a3b3c2’.

Input and Output Format

• Input consists of a string.
• The output of a string with an integer value.

Refer sample output for formatting specifications

Sample Input 1:

aaaXXXccc

Sample Output 1:

a3 X3 c3

Java Program to Count of Occurrence of each character

Following are the steps to find the court of occurrence of each character in string in Java:

• Input a string from the user.
• Declare a HashMap of Character and Integer.
• Convert string to character array using toCharArray() method.
• Iterate over the HashMap and check for the following condition
  • If traverse character is present increment map’s value to 1.
  • Otherwise, Add 1 to its map value.
• At last, print the character and its count of value by traversing the HashMap.

package com.company;

import java.util.HashMap;
import java.util.Map;
import java.util.Scanner;

public class Practice12 {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        String str = scanner.nextLine();
        HashMap<Character,Integer> map = new HashMap<>();
        char c[] = str.toCharArray();
        for(char char1:c){
            if(map.containsKey(char1))
                map.put(char1,map.get(char1)+1);
            else
                map.put(char1,1);
        }
        for(Map.Entry entry: map.entrySet()){
            System.out.print(entry.getKey()+""+entry.getValue()+" ");
        }
    }

}

Output

Thus, in this way, we learn How to find the count of sequential characters along with finding the frequency of characters in a given string with HashMap and without HashMap.