java创建对象的5种方式

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1.new
2.使用反射Class.forName(“com.cn.mybatisDemo.util.Student”).newInstance()或Student.class.newInstance();
3.使用构造器
Constructor constructor=Student.class.getConstructor();
Student newInstance = constructor.newInstance();
或Student student4 = Student.class.getConstructor().newInstance();
4.clone()
必须在实体类中实现Cloneable接口，重写clone()方法，并将其改为public修饰，Cloneable接口和我们在编写IO程序的时候序列化接口一样，只是一个标志，这个接口是不包含任何方法的，这个标志主要是为了检测Object类中的clone方法，若我们定义的类想要实现拷贝功能，但是没有实现该接口而调用Object的clone方法，那么就会出现语句中catch块里面的异常错误，抛出CloneNotSupportedException。
5.使用反序列化的方式，切记实体需要实现Serializable接口

import java.io.Serializable;

public class Student implements Cloneable,Serializable{
private int id;
private String name;
private int age;
private String sex;
private String content;

public Student() {}public Student(int id, String name, int age, String sex, String content) {    super();    this.id = id;    this.name = name;    this.age = age;    this.sex = sex;    this.content = content;}public int getId() {    return id;}public void setId(int id) {    this.id = id;}public String getName() {    return name;}public void setName(String name) {    this.name = name;}public int getAge() {    return age;}public void setAge(int age) {    this.age = age;}public String getSex() {    return sex;}public void setSex(String sex) {    this.sex = sex;}public String getContent() {    return content;}public void setContent(String content) {    this.content = content;}@Overridepublic  Student clone() throws CloneNotSupportedException {    return (Student)super.clone();}

}

import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.OutputStream;
import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;

public class TestObjectCreate {
public static void main(String[] args) throws InstantiationException, IllegalAccessException,
ClassNotFoundException, IllegalArgumentException, InvocationTargetException, NoSuchMethodException,
SecurityException, CloneNotSupportedException, FileNotFoundException, IOException {

    Student student1 = new Student();    System.out.println(student1);    Student student2 = (Student) Class.forName("com.cn.mybatisDemo.util.Student").newInstance();    System.out.println(student2);    Student student3 = Student.class.newInstance();    System.out.println(student3);    Constructor<Student> constructor=Student.class.getConstructor();    Student newInstance = constructor.newInstance();    System.out.println(newInstance);    Student student4 = Student.class.getConstructor().newInstance();    System.out.println(student4);    Student student5 = student4.clone();    System.out.println(student5);    ObjectOutputStream objectOutputStream = new ObjectOutputStream(new FileOutputStream("data"));    objectOutputStream.writeObject(student5);    ObjectInputStream inputStream = new ObjectInputStream(new FileInputStream("data"));    Student student6 = (Student) inputStream.readObject();    System.out.println(student6);}

}

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