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());
}
}