Java 字元串反轉

public class Test {

  public static void main(String[] args){

   Scanner scanner = new Scanner(System.in);

   System.out.println("請輸入一個字元串");

   String s = scanner.next();

   String s1 ="";

   for(int i =s.length()-1 ;i>0;i--){

    char b =s.charAt(i);

    s1+=b;

   }

   System.out.println(s1);

  }  

}