学步园

class a{int i = 1;}

public class rf{
    public static void main(String argc[]){
       rf rf1 = new rf();
       rf1.method0();    
                                                        }
          void method0 (){
            a aa = new a();
            aa.i=10;
            method1(aa);
            System.out.println(aa.i);
                               }
           

         //传入的是aa的一个copy                                               
          void method1(a aa){
                  int i = 100;
                   aa.i = 20;
                   a bb = new a();                 
        //修改了外部aa的一个copy,因而main函数重的aa所指向的对象仍然是调用 
        //方法method1之前的那一个,所以方法method1中的赋值不改变外部对象的
        //指向,但是aa.i仍然改变了另一个对象中i的值.
                   aa = bb;
                   System.out.println(aa.i+" "+i);
                                      }  

                        }