Java 中创建对象的 5 种方式！

Java中有5种创建对象的方式，下面给出它们的例子还有它们的字节码

Employee类：

　　

class Employee implements Cloneable, Serializable {
   private static final long serialVersionUID = 1L;
   private String name;
   public Employee() {
       System.out.println("Employee Constructor Called...");
   }
   public String getName() {
       return name;
   }
   public void setName(String name) {
       this.name = name;
   }
   @Override
   public int hashCode() {
       final int prime = 31;
       int result = 1;
       result = prime * result + ((name == null) ? 0 : name.hashCode());
       return result;
   }
   @Override
   public boolean equals(Object obj) {
       if (this == obj)
           return true;
       if (obj == null)
           return false;
       if (getClass() != obj.getClass())
           return false;
       Employee other = (Employee) obj;
       if (name == null) {
           if (other.name != null)
               return false;
       } else if (!name.equals(other.name))
           return false;
       return true;
   }
   @Override
   public String toString() {
       return "Employee [name=" + name + "]";
   }
   @Override
   public Object clone() {
       Object obj = null;
       try {
           obj = super.clone();
       } catch (CloneNotSupportedException e) {
           e.printStackTrace();
       }
       return obj;
   }
}

下面的Java程序中，我们将用5种方式创建Employee对象。

public class ObjectCreation {
   public static void main(String... args) throws Exception {
       // 1.使用new关键字
       Employee emp1 = new Employee();
       emp1.setName("Naresh");
       System.out.println(emp1 + ", hashcode : " + emp1.hashCode());
       // 2.  使用Class类的newInstance方法
       Employee emp2 = (Employee) Class.forName("org.programming.mitra.exercises.Employee")
                              .newInstance();
       // 或者这样
       // Employee emp2 = Employee.class.newInstance();
       emp2.setName("Rishi");
       System.out.println(emp2 + ", hashcode : " + emp2.hashCode());
       // 3.使用Constructor类的newInstance方法
       Constructor<Employee> constructor = Employee.class.getConstructor();
       Employee emp3 = constructor.newInstance();
       emp3.setName("Yogesh");
       System.out.println(emp3 + ", hashcode : " + emp3.hashCode());
       // 4.使用clone方法
       Employee emp4 = (Employee) emp3.clone();
       emp4.setName("Atul");
       System.out.println(emp4 + ", hashcode : " + emp4.hashCode());
       // 5.使用反序列化
       // Serialization
       ObjectOutputStream out = new ObjectOutputStream(new FileOutputStream("data.obj"));
       out.writeObject(emp4);
       out.close();
       //Deserialization
       ObjectInputStream in = new ObjectInputStream(new FileInputStream("data.obj"));
       Employee emp5 = (Employee) in.readObject();
       in.close();
       emp5.setName("Akash");
        //居然用对象流写入一个对象，再读出一个对象
       System.out.println(emp5 + ", hashcode : " + emp5.hashCode());
   }
}