java实例化对象的五种方式

1、用new语句创建对象，这是最常见的创建对象的方法。

Student student = new Student();

2、通过工厂方法返回对象，如：String str = String.valueOf(23); 

public interface Factory{

    Product createProduct();
}
public class ConcreateFactory implements Factory{

}
public Product createProduct(){

    return new ConcreateProduct(); 
}
public class ConcreateProduct implements Product{}

} 
public interface Product{}
private Factory factory;

public class Client{
this.factory = factory;

public Client(Factory factory){ }
Product product = factory.createProduct();

public void dosomething(){ }
Client client = new Client(new ConcreateFactory());

public static void main(String[] args){ client.dosomething(); }
}

3、运用反射手段,调用java.lang.Class或者java.lang.reflect.Constructor类的newInstance()实例方法。如：Object obj = Class.forName("java.lang.Object").newInstance(); 

c1 = Class.forName('com.ghgj.reflect.Student');
Student student3 = (Student)c1.newInstance();

4、调用对象的clone()方法。Student student2 = (Student) student.clone()

Student student2 = (Student) student.clone();

5、通过I/O流（包括反序列化），如运用反序列化手段，调用java.io.ObjectInputStream对象的 readObject()方法。

ObjectOutputStream out = new ObjectOutputStream (new FileOutputStream("C:/student.txt"));
out.writeObject(student);
out.close();
ObjectInputStream in = new ObjectInputStream(new FileInputStream("C:/student.txt"));
Student student4 = (Student)in.readObject();
in.close();