关于Java clone（浅克隆） 的代码

 1 import java.util.Date;
 2 
 3 public class HelloWorld{
 4     public static void main(String[] args) throws CloneNotSupportedException{
 5         Student stu1 = new Student();
 6         Student stu2 = (Student)stu1.clone(stu1);
 7         
 8         System.out.println(stu1);
 9         System.out.println(stu2);
10         System.out.println(stu1 == stu2);
11         System.out.println(stu1.createDate == stu2.createDate);
12         
13         stu2.createDate = new Date();
14         stu2.name = "TomCat";
15         stu2.age = 2333;
16         
17         System.out.println(stu1);
18         System.out.println(stu2);
19         
20         System.out.println(stu1.createDate == stu2.createDate);
21         
22     }
23 }
24 class Student implements Cloneable {
25     public Date createDate = new Date();
26     public String name;
27     public int age;
28     
29     public Student() {
30         this("Stupid", 18);
31     }
32     
33     public Student(String name, int age) {
34         this.name = name;
35         this.age = age;
36     }
37     
38     public Object clone(Object o) throws CloneNotSupportedException {
39         return super.clone();
40     }
41 
42     @Override
43     public String toString() {
44         return "Student [createDate=" + createDate + ", name=" + name + ", age=" + age + "]";
45     }
46 }

Student [createDate=Fri Jul 28 19:46:06 CST 2017, name=Stupid, age=18]
Student [createDate=Fri Jul 28 19:46:06 CST 2017, name=Stupid, age=18]
false
true
Student [createDate=Fri Jul 28 19:46:06 CST 2017, name=Stupid, age=18]
Student [createDate=Fri Jul 28 19:46:06 CST 2017, name=TomCat, age=2333]
false

1 stu2.createDate.setYear(1900);

Student [createDate=Fri Jul 28 19:51:05 CST 2017, name=Stupid, age=18]
Student [createDate=Fri Jul 28 19:51:05 CST 2017, name=Stupid, age=18]
false
true
Student [createDate=Mon Jul 28 19:51:05 CST 3800, name=Stupid, age=18]
Student [createDate=Mon Jul 28 19:51:05 CST 3800, name=TomCat, age=2333]
true