执行方法后不应该对象a ，b的指向交换吗？求指点！！！

public class Text16 {      public static void main(String[] args) {         Circle a = new Circle(1);         Circle b = new Circle(2);         method(a,b);         System.out.println("一、a半径："+a.radius+"，b半径："+b.radius);     }     public static void method(Circle x,Circle y){         Circle tmp = x;         x = y;         y = tmp;     }      } class Circle{     double radius;     Circle(double x){         radius = x;     } }