java实例化一个对象的方式

一.new(经过构造函数)

二.反射(经过构造函数)

三.反序列化(不经过构造函数)

四.克隆(不经过构造函数)

 

package com.wen1024;

public class NewInstance {

    public static void main(String[] args) throws Exception {

        //1、使用new的方式------通过有参构造函数

        Customer customer1 = new Customer("张三", 18);

        System.out.println("customer1:" + customer1);

        //2、使用反射------通过无参构造函数

        Customer customer2 = (Customer) Class.forName("com.itheima.Customer").newInstance();

        System.out.println("customer2:" + customer2);

        //3、使用克隆(需要实现Cloneable接口，重写Object类中的clone方法)------不通过构造函数

        Customer customer3 = (Customer) customer1.clone();

        System.out.println("customer3:" + customer3);

    }

}

 

 

 

package com.wen1024;

import java.io.*;

import java.util.Date;

public class Deserialize {

    public static void main(String[] args) throws Exception {

        // 4、通过反序列化创建对象

        //其中的  C:\Users\Administrator\Desktop\serializable.txt 表示存放序列化对象的文件

        //序列化对象

        ObjectOutputStream out = new ObjectOutputStream(new FileOutputStream("C:\\Users\\Administrator\\Desktop\\serializable.obj"));

        Customer customer = new Customer("张三", 18);

        System.out.println(customer);

        //写入customer对象

        out.writeObject(customer);

        out.flush();

        out.close();

        //反序列化对象

        ObjectInputStream in = new ObjectInputStream(new FileInputStream("C:\\Users\\Administrator\\Desktop\\serializable.obj"));

        //读取customer对象

        Customer obj = (Customer) in.readObject();

        System.out.println(obj);

        System.out.println(customer == obj);

        in.close();

    }

}