Valid Palindrome

class Solution {
    public boolean isPalindrome(String s) {
        String line = "";
        String reverse = "";
        for(int i = 0; i<s.length(); i++){
            if((s.charAt(i) >= 'A' && s.charAt(i)<='Z') || (s.charAt(i) >= 'a' && s.charAt(i)<='z') ||(s.charAt(i)>='0' && s.charAt(i)<='9')){
                line += s.charAt(i)+"";
            }
        }
        line = line.toLowerCase();
        //System.out.println(line);
        return reverse(line).equals(line);
    }
    
    public static String reverse(String a){
        String result = "";
        for(int i = a.length()-1; i>=0; i--){
            result += a.charAt(i);
        }
        
        return result;
    }
    
    
}