Count Particular character in string

import java.util.Arrays;

public class BasicProgram {


    // count character
    // Newton 0 index 
    public static int countCharacter (String s , char ch) {
        int count  = 0;
        for(int i=0;i<s.length();i++) {
        if(s.charAt(i) == Character.toLowerCase(ch) ) {
            count++;
        }
        }
        return count;
    } 
  public static void main(String[] args) {
      // String data type which is used to store the data that data should be text
      // if enclosed any anything between double quoted symbol that is string
     // How to decalre the string

   

     // anything between the '' it will consider that as a character  => character should be one
    // print and println method only except  string or integrer array
     System.out.println();
   // plus operator in string
   // it will concatenate two string or you can say it will add two string into the single string
  
   // I want to calculate the how many type particular character present in given string

   String variableName = "Newton";
   System.out.println("What are you doing : " +variableName);
   // calling count character Method ignore cases

   int a = countCharacter(variableName.toLowerCase() , 'n');
   System.out.println("Count of character: " + a);

  }

}