java創建對象的方式

2019-11-06 06:48:23

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java創建對象的方式

1、直接new2、通過反射clazz的newInstance調用無參構造函數創建對象3、通過反射獲取構造函數直接newInstance創建對象4、實現Serializable接口，通過反系列化創建對象5、實現Cloneable接口，覆蓋clone方法，通過克隆創建對象package cn.zlz.createobj;import java.io.FileInputStream;import java.io.FileOutputStream;import java.io.ObjectInputStream;import java.io.ObjectOutputStream;import java.lang.reflect.Constructor;/** * 創建對象的方式 * 1、直接new * 2、通過反射clazz的newInstance調用無參構造函數創建對象 * 3、通過反射獲取構造函數直接newInstance創建對象 * 4、實現Serializable接口，通過反系列化創建對象 * 5、實現Cloneable接口，覆蓋clone方法，通過克隆創建對象 * */public class Main { public static void main(String[] args) { // 通過構造函數直接new Person person = new Person(); System.out.PRintln(person); // 通過反射創建對象 createByReflect(); // 通過構造器反射創建對象 createByConstructor(); // 通過序列化創建對象 createBySerialize(); //通過克隆創建對象 createByClone(); } private static void createByClone() { Person person = new Person("wangwu",5); Person clone = person.clone(); System.out.println(clone); } private static void createBySerialize() { try { String filePath = "person.dat"; Person instance = new Person("lizi",4); ObjectOutputStream objectOutputStream = new ObjectOutputStream(new FileOutputStream( filePath)); objectOutputStream.writeObject(instance); ObjectInputStream objectInputStream = new ObjectInputStream(new FileInputStream(filePath)); Person person = (Person) objectInputStream.readObject(); System.out.println(person); } catch (Exception e) { // TODO Auto-generated catch block e.printStackTrace(); } } private static void createByConstructor() { try { Class<?> clazz = Class.forName("cn.zlz.createobj.Person"); Constructor<?> constructor = clazz.getDeclaredConstructor(String.class, int.class); Person person = (Person) constructor.newInstance("zhangsan", 2); System.out.println(person); } catch (Exception e) { // TODO Auto-generated catch block e.printStackTrace(); } } private static void createByReflect() { try { Class<?> clazz = Class.forName("cn.zlz.createobj.Person"); Person person = (Person) clazz.newInstance(); System.out.println(person); } catch (Exception e) { // TODO Auto-generated catch block e.printStackTrace(); } }}package cn.zlz.createobj;import java.io.Serializable;public class Person implements Serializable, Cloneable { /** * */ private static final long serialVersionUID = 1L; private String name; private int age; public Person(String name, int age) { super(); this.name = name; this.age = age; } public Person() { super(); } @Override public String toString() { return "Person [name=" + name + ", age=" + age + "]"; } @Override public Person clone() { Person person = null; try { return (Person) super.clone(); } catch (CloneNotSupportedException e) { e.printStackTrace(); } return person; }}

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