Java通用类 - 确定类型 [英] Java Generic Class - Determine Type

问题描述

如果我将java类创建为通用类，如：

  public class Foo< T> 
  

在内部如何确定这个班级，最后是什么'T'？

  public ???? Bar（）
 {
 //如果其类型1 
 //执行此操作
 //如果其类型2 
 //执行此操作
 //如果它的类型3 
 //做这个
 //如果它的类型4 
 //做这个
} 
  

我使用了Java API，并且使用了Reflection的东西，instanceof，getClass，.class等，但我似乎无法做出正面或反面的评论他们。我觉得我很接近，只需要结合一些电话，但不断缩短。

更具体地说，我试图确定类被实例化为3种可能的类型之一。

解决方案

我已经使用了类似的解决方案，项目，并发现它非常有用。

http://blog.xebia.com/2009/02/07/acessing-generic-types-at-runtime-in-java/ <

公共类returnedclass（） ）{
ParameterizedType parameterizedType =（ParameterizedType）getClass（）
.getGenericSuperclass（）;
return（Class）parameterizedType.getActualTypeArguments（）[0];
}

If I am creating a java class to be generic, such as:

public class Foo<T>

How can one determine internally to that class, what 'T' ended up being?

public ???? Bar()
{
    //if its type 1
    //    do this
    //if its type 2
    //    do this
    //if its type 3
    //    do this
    //if its type 4
    //    do this
}

I've poked around the Java API and played with the Reflection stuff, instanceof, getClass, .class, etc, but I can't seem to make heads or tails of them. I feel like I'm close and just need to combine a number of calls, but keep coming up short.

To be more specific, I am attempting to determine whether the class was instantiated with one of 3 possible types.

解决方案

I've used a similar solution to what he explains here for a few projects and found it pretty useful.

http://blog.xebia.com/2009/02/07/acessing-generic-types-at-runtime-in-java/

The jist of it is using the following:

 public Class returnedClass() {
     ParameterizedType parameterizedType = (ParameterizedType)getClass()
                                                 .getGenericSuperclass();
     return (Class) parameterizedType.getActualTypeArguments()[0];
}

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