java中的clone()方法的研究---(7)如何编写正确的clone()方法：Date, Timestamp

五：Date, Timestamp类型

在自定义类Person中添加新的属性：Date, Timestamp

package tt.vo;

import java.sql.Timestamp;
import java.util.Arrays;
import java.util.Date;

public class Person implements Cloneable {

  // 基本数据类型
  private int age;

  // Wrapper Class类型
  private Integer height;

  // String 类型
  private String name;

  // StringBuffer
  private StringBuffer address1;

  // StringBuilder
  private StringBuilder address2;

  // Date
  private Date date;

  // Timestamp
  private Timestamp timestamp;
  
  @Override
  public Person clone() throws CloneNotSupportedException {
    Person p = (Person) super.clone();

    // StringBuffer,StringBuilder 没有实现clone方法
    // 只能用 new
    p.address1 = new StringBuffer(this.address1);
    p.address2 = new StringBuilder(this.address2);
    
    p.date = (Date)this.date.clone();
    p.timestamp = (Timestamp)this.timestamp.clone();

    return p;
  }

  public int getAge() {
    return age;
  }

  public void setAge(int age) {
    this.age = age;
  }

  public Integer getHeight() {
    return height;
  }

  public void setHeight(Integer height) {
    this.height = height;
  }

  public String getName() {
    return name;
  }

  public void setName(String name) {
    this.name = name;
  }

  public StringBuffer getAddress1() {
    return address1;
  }

  public void setAddress1(StringBuffer address1) {
    this.address1 = address1;
  }

  public StringBuilder getAddress2() {
    return address2;
  }

  public void setAddress2(StringBuilder address2) {
    this.address2 = address2;
  }

  @Override
  public String toString() {
    return "Person [age=" + age + ", height=" + height + ", name=" + name
        + ", address1=" + address1 + ", address2=" + address2
        + ", date=" + date + ", timestamp=" + timestamp + "]";
  }

  public Date getDate() {
    return date;
  }

  public void setDate(Date date) {
    this.date = date;
  }

  public Timestamp getTimestamp() {
    return timestamp;
  }

  public void setTimestamp(Timestamp timestamp) {
    this.timestamp = timestamp;
  }

}

注意，这里的clone()方法，针对Date, Timestamp这两种类型的克隆，我是直接贴出来正确的写法。

只有调用date.clone()，timestamp.clone() 才是深克隆。

@Override
  public Person clone() throws CloneNotSupportedException {
    Person p = (Person) super.clone();

    // StringBuffer,StringBuilder 没有实现clone方法
    // 只能用 new
    p.address1 = new StringBuffer(this.address1);
    p.address2 = new StringBuilder(this.address2);
    
    p.date = (Date)this.date.clone(); // Date 有clone方法
    p.timestamp = (Timestamp)this.timestamp.clone();  // Timestamp 有clone方法

    return p;
  }

---------------------------------------------------------------下面开始测试了------------------------------------------------------------------

测试类TestMain：

package tt;

import java.sql.Timestamp;
import java.util.Date;

import tt.vo.Person;

public class TestMain {

  public static void main(String[] args) throws CloneNotSupportedException {
    // initialize Person p
    Person p = new Person();
    
    // int 
    p.setAge(18);
    
    // Integer
    p.setHeight(162);
    
    // String
    p.setName("郭美美");
    
    // StringBuffer
    p.setAddress1(new StringBuffer("中国北京"));
    
    // StringBuilder
    p.setAddress2(new StringBuilder("美国纽约"));
    
    // Date
    p.setDate(new Date());
    
    // Timestamp
    p.setTimestamp(new Timestamp(123456789l));
    
    System.out.println("p:" + p);
    Person pclone = p.clone();
    System.out.println("pclone:" + pclone);
    
    
    
    
    System.out.println("-------------after set-------------------");
    
    p.setAge(180);  
    p.setHeight(190);
    p.setName("郭美美不美");
    pclone.getAddress1().append("!!!");
    pclone.getAddress2().append("......");
    
    p.getDate().setYear(2000);
    p.getTimestamp().setYear(3000);
    
    
    System.out.println("p:" + p);
    System.out.println("pclone:" + pclone);
  }

  
  
}

debug截图：

成功克隆的pclone.data,pclone.timestamp id 与原来的不同。

修改了 p.getDate().setYear(2000); p.getTimestamp().setYear(3000); 之后，我们来看看控制台打印的结果。

很令人满意~~~

p:Person [age=180, height=190, name=郭美美不美, address1=中国北京, address2=美国纽约, date=Mon Jun 11 16:37:42 CST 3900, timestamp=4900-01-02 18:17:36.789]
pclone:Person [age=18, height=162, name=郭美美, address1=中国北京!!!, address2=美国纽约......,date=Thu Jun 11 16:37:42 CST 2015, timestamp=1970-01-02 18:17:36.789]