[leetcode]Valid Palindrome-回文验证 java

注意以下项

1. 空字符串也是回文

 

public class Solution {
    public boolean isPalindrome(String s) {
        if(s.equals("")){
            return true;
        }
        s = s.toLowerCase();
        StringBuilder clearStr = new StringBuilder();
        for(int i=0; i<s.length(); i++){
            char c = s.charAt(i);
            if(c>=48 && c<=57){
                clearStr.append(c);
            }
            if(c>=97 && c<=122){
                clearStr.append(c);
            }
        }
        String str = clearStr.toString();
        String reverseStr = clearStr.reverse().toString();
        if(str.equals(reverseStr)){
            return true;
        }
        return false;    
    }
}