如何以最好的方式从类对象创建一个实例 [英] how to create in best way an instance from the class object

问题描述

有一种方法可以避免慢速反射从一个类创建一个实例，显然在另一个方法中？例如：

There is a way to avoid the slow reflection to create an instance from a class, obviously within another method ? For example:

Foo foo = new Foo();
foo.create(Dog.class, "rocky");

class Foo {
    Object create(Class object, String dogName) {
        //create an instance of the class 'object' here passing the argument to constructor
        //e.g. Object obj = new object(dogName); <-- this is wrong

        return obj;
    }
}

class Dog extends Animal {
   Dog(String dogName) {
       this.name = dogName;
   }
}

class Animal {
    String name;
}

$ b $ p我无法使用关键字new创建实例，在另一种方法中的实例以动态的方式...

I cannot create the instance using the keyword "new", because I must create the instance in another method in a dynamic way...

你有最好的方式（如性能）改进这个代码:)谢谢！ p>

You have carte blanche to improve in the best way (like performance) this code :) Thank you!

推荐答案

让你的Dog和Animal类保持一致。并使用Builder模式

Leave your Dog and Animal classes the same. and use the Builder pattern

  public interface Builder<T> {
  public T build(String nameString);
}
public static void main(String[] args){
  Builder<Dog> builder =  new Builder<Dog>()
  {

     @Override
     public Dog build(String nameString)
     {
        return new Dog(nameString);
     }

  };
 Dog dog = builder.build("Rocky");
 System.out.print(dog.name);

}

a href =http://stackoverflow.com/questions/299998/instantiating-object-of-type-parameter>类型参数的实例化对象也会进一步解释。

The answers over at Instantiating object of type parameter explain it further as well.

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