Java中 对象克隆实例

import java.util.*;public class CloneTest {    public static void main(String[] args) {        // TODO Auto-generated method stub        try {            Employee original = new Employee("John Q,publi c", 5000);            original.setHireDay(2000, 1, 1);            Employee copy = original.clone();            copy.raiseSalary(10);            copy.setHireDay(2002, 12, 31);            System.out.println("original=" + original);            System.out.println("copy+" + copy);        } catch (CloneNotSupportedException e) {            e.printStackTrace();        }    }}//Cloneable 仅作为 clone 接口的标记，表明类设计者知道要进行克隆处理//标记接口class Employee implements Cloneable{    public Employee(String n, double s) {        name = n;        salary = s;        hireDay = new Date();    }    public Employee clone() throws CloneNotSupportedException {        //使用Object.clone方法时如果对象中的所有数据域都属于数值类型和基本类型，则所有拷贝没问题        //但如果在对象中包含了子对象的引用，拷贝结果会使得两个域引用同一个子对象，因此原始对象和克隆对象共享这些信息        Employee cloned = (Employee) super.clone();        //为了实现深拷贝，鼻血克隆所有肯变的实例域        cloned.hireDay = (Date) hireDay.clone();        return cloned;    }    public void setHireDay(int year, int month, int day) {        Date newHireDay = new GregorianCalendar(year, month - 1, day).getTime();        hireDay.setTime(newHireDay.getTime());    }    public void raiseSalary(double byPercent) {        double raise = salary * byPercent / 100;        salary += raise;    }    public String toString() {        return "Employee[name=" + name + ",salary=" + salary + ",hireDay=" + hireDay + "]";    }    private String name;    private double salary;    private Date hireDay;}

public interface Cloneable此类实现了 Cloneable 接口，以指示 Object.clone() 方法可以合法地对该类实例进行按字段复制。

如果在没有实现 Cloneable 接口的实例上调用 Object 的 clone 方法，则会导致抛出 CloneNotSupportedException 异常