JAVA回文

package huiwen;
import java.util.Scanner;
public class Huiwen {
public static void main(String[] args) {
	// TODO Auto-generated method stub
	String s;
	int j;
	int i = 0;
	Scanner input = new Scanner(System.in);
	System.out.println("请输入 一个字符串：");
	s = input.next();
	char a[];
	a = s.toCharArray();
	j = a.length - 1;
	for (int k = 0; k < s.length(); k++) {
		System.out.print(a[k]);
	}
	huiwen(a, j, i);
}

public static void huiwen(char a[], int j, int i) {
	if (i >= j) {
		if (a[i] == a[j])

			System.out.println("是回文");
		System.exit(0);
	}
	if (a[i] == a[j])
		huiwen(a, --j, ++i);
	else {
		System.out.println("不是回文！");
		System.exit(0);
	}
}
}