递归回文

package ketangceshia;

import java.util.Scanner;

public class HuiWendg {
    public static void main( String args[] )
    {
        Scanner scan=new Scanner(System.in);
        String a=scan.next();
        int n=a.length();
        if(a.length()==0)//字符串长度为0时
            System.out.println("是回文！");
        else
        {
            boolean b=isHuiWen(a,0,n);
            if(b==true)
                System.out.println("是回文！");
            else
                if(b==false)
                    System.out.println("不是回文！");
        }
    }
    private static boolean isHuiWen(String str, int start, int length) {
        if(start==length)
            return true;
        else if(str.toCharArray()[start]==str.toCharArray()[length-1]){
            return isHuiWen(str,start+1,length-1);
    }
    return false;
    }
}