如何用Java来判断回文数？

public class  palindrome {
    public static boolean isPalindrome(String str)        
    {
        SqStackClass<Character> st = new SqStackClass();    //建立一个顺序栈
        int n = str.length();
        int i = 0;
        while (i < n / 2)                    //将str前半字符进栈
        {
            st.push(str.charAt(i));
            i++;                        //继续遍历str
        }
        if (n % 2 == 1)                        //n为奇数时
            i++;                        //跳过中间的字符
        while (i < n)                        //遍历str的后半字符
        {
            if (st.pop() != str.charAt(i))
                return false;            //若str[i]不等于出栈字符返回false
            i++;
        }
        return true;                    //是回文返回true
    }
    public static void main(String[] args) {
        System.out.println("测试1");
        String str = "abcba";
        if (isPalindrome(str))
            System.out.println(str + "是回文");
        else
            System.out.println(str + "不是回文");
        System.out.println("测试2");
        str = "1221";
        if (isPalindrome(str))
            System.out.println(str + "是回文");
        else
            System.out.println(str + "不是回文");
    }
}