JadenCase 문자열 만들기

https://school.programmers.co.kr/learn/courses/30/lessons/12951?language=java

class Solution {
    public String solution(String s) {
        
        String lowStr = s.toLowerCase();
        StringBuilder sb = new StringBuilder();
        for(int i = 0; i < lowStr.length(); ++i)
            sb.append(lowStr.charAt(i));
    
        if(isAlpha(sb.charAt(0)))
            sb.setCharAt(0, (char)(sb.charAt(0)-32));
        
        for(int i = 1; i < sb.length(); ++i)
        {
            if(sb.charAt(i-1) == ' ')
            {
                if(isAlpha(sb.charAt(i)))
                    sb.setCharAt(i, (char)(sb.charAt(i)-32));
            }
          
        }
        
        return sb.toString();
    }
    
    public static boolean isAlpha(Character c)
    {
        if(c != ' ' && false == isNum(c))
            return true;
        
        return false;
    }
    
    public static boolean isNum(Character c)
    {
        if(c >= '0' && c <= '9')
            return true;
        
        return false;
    }
}