Sum of Digits of String After Convert.java

class Solution {
    public int getLucky(String s, int k) {
    
        StringBuilder sb=new StringBuilder();

        for(int i=0;i<s.length();i++)
        sb.append((s.charAt(i)-'a')+1);
        String result=sb.toString();
 
        if(result.length()==1)
        return Character.getNumericValue(result.charAt(0));
        
        int sum=0;
        while(k-->0 && result.length()>1)
        {   
            sum=0;
            for(int i=0;i<result.length();i++)
            sum+=Character.getNumericValue(result.charAt(i));
            
            result=String.valueOf(sum);
        }
        
        return sum;   
    }
}