回文

package huiwen;
import java.util.Scanner;
public class Huiwen {
public static void main(String[] args) {
    String s;
    int w;
    int q = 0;
    Scanner input = new Scanner(System.in);
    System.out.println("输入一串字母：");
    s = input.next();
    char a[];
   a = s.toCharArray();
    w = a.length - 1;
    for (int k = 0; k < s.length(); k++) {
        System.out.print(a[k]);
    }
    huiwen(a, w, q);
}
 
public static void huiwen(char a[], int w, int q) {
    if (q >= w) {
        if (a[q] == a[w])
 
            System.out.println("是"); 
        System.exit(0);
    }
    if (a[q] == a[w])
        huiwen(a, --w, ++q);
    else {
        System.out.println("不是！");
        System.exit(0);
    }
}
}