Checking the String is palindrome or not in java

Java Program :

pallindromeDayOne.java
public class pallindromeDayOne {
    public static boolean checkPallindrome(String str){
        boolean res=false;
        if (str.length()==0||str.length()==1) return res;

        int start = 0, end = str.length()-1;
        while (start<end){
            res= str.charAt(start) == str.charAt(end);
            start++; end--;
        }
        return res;
    }
    public static void main(String[] args) {
        System.out.println(checkPallindrome("abckcba")? "string is palindrome":"not palindrome" );
    }
}

simplified and extended program :

public class pallindromeDayOne {
    public static boolean checkPallindrome(String str){
        boolean res=false;
        if (str.length()==0||str.length()==1) return res;

        int start = 0, end = str.length()-1;
        while (start<end){
            if (str.charAt(start) == str.charAt(end)) {
                res = true;
            } else {
                res = false;
            }
            start++; end--;
        }
        return res;
    }
    public static void main(String[] args) {
        if (checkPallindrome("abckcba")== true) {
            System.out.println("string is palindrome");
        } else {
            System.out.println("not palindrome");
        }
    }
}