对象赋值

在为对象“赋值”的时候，情况却发生了变化。对一个对象进行操作时，我们真正操作
的是对对象的引用。所以倘若“将一个对象赋值给另一个对象”，实际是将“引用”从一个
地方复制到另一个地方。这意味着假若对对象使用“c=d”，那么c和d都指向原本只有d
指向的那个对象。下面这个例子将向大家阐示这一点。  

//: c03:Assignment.java 

// Assignment with objects is a bit tricky. 

import com.bruceeckel.simpletest.*; 

 

class Number { 

 int i; 

} 

 

public class Assignment { 

 static Test monitor = new Test(); 

 public static void main(String[] args) { 

 Number n1 = new Number(); 

 Number n2 = new Number(); 

 n1.i = 9; 

 n2.i = 47; 

 System.out.println("1: n1.i: " + n1.i + 

 ", n2.i: " + n2.i); 

 n1 = n2; 

 System.out.println("2: n1.i: " + n1.i + 

 ", n2.i: " + n2.i); 

 n1.i = 27; 

 System.out.println("3: n1.i: " + n1.i + 

 ", n2.i: " + n2.i); 


 monitor.expect(new String[] { 

 "1: n1.i: 9, n2.i: 47", 

 "2: n1.i: 47, n2.i: 47", 

 "3: n1.i: 27, n2.i: 27" 

 }); 

 } 

} ///:~