JAVA classroom topic - recursion to determine the number of return

package class20190923;

import java.util.Scanner;

public class Classtext {
    private static int n=0;
    private static String str1,str2;
    public static void main(String[] args) {
        String str1,str2;
        Scanner sc = new Scanner(System.in);
        str1=sc.nextLine();
        if(str1.length()==1||str1.length()==0)
            System.out.println("yes");
        else {
                pd1(str1,n);    
        }
    }
    public static void pd1(String str,int x) {
        n=x;
        if(n==(str.length()/2)||n==((str.length()+1)/2))
        {
            System.out.println("yes");
            return ;
        }
        else if(str.charAt(n)==str.charAt(str.length()-n-1))
        {
            pd1(str,n+1);
        }
        else if(str.charAt(n)!=str.charAt(str.length()-n-1))
        {
            System.out.println("no");
            return ;}

    }
}

operation result